place argued march decided june respondent behavior aroused suspicion law enforcement officers waited line miami international airport purchase ticket new york la guardia airport officers approached respondent requested received identification respondent consented search two suitcases checked flight depart officers decided search luggage officers found discrepancies address tags luggage called drug enforcement administration dea authorities new york relay information upon respondent arrival la guardia airport two dea agents approached said believed might carrying narcotics asked received identification respondent refused consent search luggage one agents told going take federal judge obtain search warrant agents took luggage kennedy airport subjected sniff test trained narcotics detection dog reacted positively one suitcases point minutes elapsed since seizure luggage thereafter agents obtained search warrant suitcase upon opening discovered cocaine respondent indicted possession cocaine intent distribute district denied motion suppress contents suitcase pleaded guilty charge convicted reserved right appeal denial motion suppress appeals reversed holding prolonged seizure respondent luggage exceeded limits type investigative stop permitted terry ohio hence amounted seizure without probable cause violation fourth amendment held circumstances seizure respondent luggage violated fourth amendment accordingly evidence obtained subsequent search luggage inadmissible respondent conviction must reversed pp officer observations lead reasonably believe traveler carrying luggage contains narcotics principles terry progeny permit officer detain luggage temporarily investigate circumstances aroused officer suspicion provided investigative detention properly limited scope pp investigative procedure subjecting luggage sniff test narcotics detection dog constitute search within meaning fourth amendment pp police seize luggage suspect custody limitations applicable investigative detentions person define permissible scope investigative detention luggage less probable cause standard police conduct exceeded permissible limits investigative stop length detention respondent luggage alone precludes conclusion seizure reasonable absence probable cause fourth amendment violation exacerbated dea agents failure inform respondent accurately place transporting luggage length time might dispossessed arrangements made return luggage investigation dispelled suspicion pp delivered opinion burger white powell rehnquist stevens joined brennan filed opinion concurring result marshall joined post blackmun filed opinion concurring judgment marshall joined post alan horowitz argued cause briefs solicitor general lee assistant attorney general jensen deputy solicitor general frey john fichter de pue james clark argued cause filed brief respondent richard emery charles sims filed brief american civil liberties union et al amici curiae urging affirmance fred inbau wayne schmidt james manak evelle younger howard berringer filed brief americans effective law enforcement et al amici curiae urging reversal justice delivered opinion case presents issue whether fourth amendment prohibits law enforcement authorities temporarily detaining personal luggage exposure trained narcotics detection dog basis reasonable suspicion luggage contains narcotics given enforcement problems associated detection narcotics trafficking minimal intrusion properly limited detention entail conclude fourth amendment prohibit detention facts case however hold police conduct exceeded bounds permissible investigative detention luggage respondent raymond place behavior aroused suspicions law enforcement officers waited line miami international airport purchase ticket new york la guardia airport place proceeded gate flight agents approached requested airline ticket identification place complied request consented search two suitcases checked flight depart however agents decided search luggage prompted place parting remark recognized police agents inspected address tags checked luggage noted discrepancies two street addresses investigation revealed neither address existed telephone number place given airline belonged third address street basis encounter place information miami agents called drug enforcement administration dea authorities new york relay information place two dea agents waited place arrival gate la guardia airport new york behavior aroused suspicion agents claimed two bags called limousine agents decided approach identified federal narcotics agents place responded knew cops spotted soon deplaned one agents informed place based observations information obtained miami authorities believed might carrying narcotics identifying bags belonging place stated number police miami airport surrounded searched baggage agents responded information contrary agents requested received identification place new jersey driver license agents later ran computer check disclosed offenses airline ticket receipt place refused consent search luggage one agents told going take luggage federal judge try obtain search warrant place free accompany place declined obtained one agents telephone numbers agents reached agents took bags kennedy airport subjected bags sniff test trained narcotics detection dog dog reacted positively smaller two bags ambiguously larger bag approximately minutes elapsed since seizure respondent luggage late friday afternoon agents retained luggage monday morning secured search warrant magistrate smaller bag upon opening bag agents discovered grams cocaine place indicted possession cocaine intent distribute violation district place moved suppress contents luggage seized la guardia airport claiming warrantless seizure luggage violated fourth amendment rights district denied motion applying standard terry ohio detention personal property concluded detention bags justified based reasonable suspicion believe bags contained narcotics finding reasonable suspicion district held place fourth amendment rights violated seizure bags dea agents supp edny place pleaded guilty possession charge reserving right appeal denial motion suppress appeal conviction appeals second circuit reversed majority assumed terry principles applied justify warrantless seizure baggage less probable cause reasonable suspicion existed justify investigatory stop place majority concluded however prolonged seizure place baggage exceeded permissible limits investigative stop consequently amounted seizure without probable cause violation fourth amendment granted certiorari affirm ii fourth amendment protects right people secure persons houses papers effects unreasonable searches seizures emphasis added although context personal property particularly containers fourth amendment challenge typically subsequent search container rather initial seizure authorities cases reveal general principles regarding seizures ordinary case viewed seizure personal property per se unreasonable within meaning fourth amendment unless accomplished pursuant judicial warrant issued upon probable cause particularly describing items seized see marron law enforcement authorities probable cause believe container holds contraband evidence crime secured warrant interpreted amendment permit seizure property pending issuance warrant examine contents exigencies circumstances demand recognized exception warrant requirement present see arkansas sanders chadwick coolidge new hampshire example objects weapons contraband found public place may seized police without warrant payton new york circumstances risk item disappearance use intended purpose warrant may obtained outweighs interest possession see also leasing case government asks us recognize reasonableness fourth amendment warrantless seizures personal luggage custody owner basis less probable cause purpose pursuing limited course investigation short opening luggage quickly confirm dispel authorities suspicion specifically asked apply principles terry ohio supra permit seizures basis reasonable articulable suspicion premised objective facts luggage contains contraband evidence crime view application appropriate terry first recognized narrow authority police officers suspect criminal activity make limited intrusions individual personal security based less probable cause michigan summers approving limited search weapons frisk individual police reasonably believed armed dangerous implicitly acknowledged authority police make forcible stop person officer reasonable articulable suspicion person engaged criminal activity implicit proposition embraced openly adams williams relied terry hold police officer lawfully made forcible stop suspect investigate informant tip suspect carrying narcotics concealed weapon see also michigan summers supra limited detention occupants authorities search premises pursuant valid search warrant cortez stop near border vehicle suspected transporting illegal aliens brief investigative stop near border questioning citizenship immigration status exception requirement limited seizures person recognized terry progeny rests balancing competing interests determine reasonableness type seizure involved within meaning fourth amendment general proscription unreasonable searches seizures must balance nature quality intrusion individual fourth amendment interests importance governmental interests alleged justify intrusion nature extent detention minimally intrusive individual fourth amendment interests opposing law enforcement interests support seizure based less probable cause examine first governmental interest offered justification brief seizure luggage suspect custody purpose pursuing limited course investigation government contends authorities possess specific articulable facts warranting reasonable belief traveler luggage contains narcotics governmental interest seizing luggage briefly pursue investigation substantial agree observed mendenhall opinion powell public compelling interest detecting traffic deadly drugs personal profit respondent suggests absent special law enforcement interest officer safety generalized interest law enforcement justify intrusion individual fourth amendment interests absence probable cause prior cases however support proposition terry described governmental interests supporting initial seizure person effective crime prevention detection interest underlies recognition police officer may appropriate circumstances appropriate manner approach person purposes investigating possibly criminal behavior even though probable cause make arrest similarly michigan summers identified three law enforcement interests justified limited detention occupants premises execution valid search warrant preventing flight event incriminating evidence found minimizing risk harm officers occupants orderly completion search cf florida royer plurality opinion predicate permitting seizures suspicion short probable cause law enforcement interests warrant limited intrusion personal security suspect test whether interests sufficiently substantial whether independent interest investigating crimes effectively apprehending suspects context particular law enforcement practice course may affect determination whether brief intrusion fourth amendment interests less probable cause essential effective criminal investigation inherently transient nature drug courier activity airports allowing police make brief investigative stops persons airports reasonable suspicion substantially enhances likelihood police able prevent flow narcotics distribution channels strong governmental interest must weigh nature extent intrusion upon individual fourth amendment rights police briefly detain luggage limited investigative purposes point respondent place urges rationale terry stop person wholly inapplicable investigative detentions personality specifically terry exception requirement premised notion stop person substantially less intrusive person liberty interests formal arrest property context however place urges degrees intrusion owner property seized dispossession absolute disagree intrusion possessory interests occasioned seizure one personal effects vary nature extent seizure may made owner relinquished control property third party immediate custody control owner moreover police may confine investigation inquiry example immediate exposure luggage trained narcotics detection dog transport property another location given fact seizures property vary intrusiveness brief detentions personal effects may minimally intrusive fourth amendment interests strong countervailing governmental interests justify seizure based specific articulable facts property contains contraband evidence crime sum conclude officer observations lead reasonably believe traveler carrying luggage contains narcotics principles terry progeny permit officer detain luggage briefly investigate circumstances aroused suspicion provided investigative detention properly limited scope purpose respondent luggage seized course arrange exposure narcotics detection dog obviously investigative procedure search requiring probable cause initial seizure respondent luggage purpose subjecting sniff test matter brief justified less probable cause see terry ohio cortez adams williams fourth amendment protects people unreasonable government intrusions legitimate expectations privacy chadwick affirmed person possesses privacy interest contents personal luggage protected fourth amendment canine sniff narcotics detection dog however require opening luggage expose noncontraband items otherwise remain hidden public view example officer rummaging contents luggage thus manner information obtained investigative technique much less intrusive typical search moreover sniff discloses presence absence narcotics contraband item thus despite fact sniff tells authorities something contents luggage information obtained limited limited disclosure also ensures owner property subjected embarrassment inconvenience entailed less discriminate intrusive investigative methods respects canine sniff sui generis aware investigative procedure limited manner information obtained content information revealed procedure therefore conclude particular course investigation agents intended pursue exposure respondent luggage located public place trained canine constitute search within meaning fourth amendment iii doubt agents made seizure place luggage purposes fourth amendment following refusal consent search agent told place going take luggage federal judge secure issuance warrant observed terry manner seizure conducted course vital part inquiry whether warranted therefore examine whether agents conduct case place seizure within general rule requiring probable cause seizure within terry exception rule outset must reject government suggestion point probable cause seizure luggage person presence becomes necessary distant case terry stop person premise government argument seizures property generally less intrusive seizures person true circumstances premise faulty facts address case precise type detention confront seizure personal luggage immediate possession suspect purpose arranging exposure narcotics detection dog particularly case detention luggage within traveler immediate possession police conduct intrudes suspect possessory interest luggage well liberty interest proceeding itinerary person whose luggage detained technically still free continue travels carry personal activities pending release luggage moreover subjected coercive atmosphere custodial confinement public indignity personally detained nevertheless seizure effectively restrain person since subjected possible disruption travel plans order remain luggage arrange return therefore police seize luggage suspect custody think limitations applicable investigative detentions person define permissible scope investigative detention person luggage less probable cause standard clear police conduct exceeded permissible limits investigative stop length detention respondent luggage alone precludes conclusion seizure reasonable absence probable cause although recognized reasonableness seizures longer momentary ones involved terry adams see michigan summers brevity invasion individual fourth amendment interests important factor determining whether seizure minimally intrusive justifiable reasonable suspicion moreover assessing effect length detention take account whether police diligently pursue investigation note new york agents knew time place scheduled arrival la guardia ample time arrange additional investigation location thereby minimized intrusion respondent fourth amendment interests thus although decline adopt outside time limitation permissible terry stop never approved seizure person prolonged period involved facts presented case see dunaway new york although detention respondent luggage sufficient render seizure unreasonable violation exacerbated failure agents accurately inform respondent place transporting luggage length time might dispossessed arrangements made return luggage investigation dispelled suspicion short hold detention respondent luggage case went beyond narrow authority possessed police detain briefly luggage reasonably suspected contain narcotics iv conclude circumstances case seizure respondent luggage unreasonable fourth amendment consequently evidence obtained subsequent search luggage inadmissible place conviction must reversed judgment appeals accordingly affirmed ordered footnotes warrant clause fourth amendment provides warrants shall issue upon probable cause supported oath affirmation particularly describing place searched persons things seized sanders explained police acted properly indeed commendably apprehending respondent luggage ample probable cause believe respondent green suitcase contained marihuana probable cause believe contraband driven away taxi police justified stopping vehicle seizing suitcase suspected contained contraband concurring opinion terry justice harlan made logical underpinning fourth amendment holding clear first place frisk justified order protect officer encounter citizen officer must first constitutional grounds insist encounter make forcible stop make perfectly clear right frisk case depends upon reasonableness forcible stop investigate suspected crime referring problem intercepting drug couriers nation airports justice powell observed much drug traffic highly organized conducted sophisticated criminal syndicates profits enormous many drugs may easily concealed result obstacles detection illegal conduct may unmatched area law enforcement mendenhall one need compare facts case van leeuwen defendant voluntarily relinquished two packages coins postal authorities several facts aroused suspicion postal officials detained packages without searching hours certain lines inquiry pursued information obtained time sufficient give authorities probable cause believe packages contained counterfeit coins obtaining warrant authorities opened packages found counterfeit coins therein resealed packages sent way expressly limiting holding facts case concluded detention packages reasonable suspicion contained contraband violate fourth amendment one commentator noted van leeuwen easy case defendant unable show invasion intruded upon either privacy interest contents packages possessory interest packages lafave search seizure supp cf florida royer supra plurality opinion agree state officers adequate grounds suspecting royer carrying drugs temporarily detaining luggage attempted verify dispel suspicions manner exceed limits investigative detention emphasis added least authorities make absolutely clear plan reunite suspect possessions future time place seizure object tantamount seizure person person must either remain scene else seemingly surrender effects permanently police lafave search seizure supp cf florida royer plurality opinion trained narcotics detection dogs used royer luggage momentarily detained investigative procedure carried course conduct also avoided substantial intrusion respondent possessory interests caused removal luggage another location cf ali model code procedure recommending maximum minutes terry stop understand desirability providing law enforcement authorities clear rule guide conduct nevertheless question wisdom rigid time limitation limit undermine equally important need allow authorities graduate responses demands particular situation justice brennan justice marshall joins concurring result case appeals assumed officers reasonable suspicion necessary justify investigative stop respondent terry ohio progeny principles terry apply seizures property see ante held simply prolonged seizure respondent baggage went far beyond mere investigative stop amounted violation fourth amendment rights see also affirm appeals judgment ground instead simply affirming ground putting end matter decides reach purportedly resolve constitutionality seizure respondent luggage less probable cause exposure luggage narcotics detection dog see ante apparently finds unable resist pull decide constitutional issues involved case broader basis record imperatively requires street new york reaches issues unnecessary judgment subscribe analysis issues concur result occasion twice recent months discuss limited scope exception fourth amendment requirement created terry progeny see florida royer brennan concurring result kolender lawson brennan concurring unfortunately unwarranted expansion exception endorses today forces elaborate previously expressed views terry expressly declined address constitutional propriety investigative seizure upon less probable cause purposes detention interrogation confronted quite narrow question whether always unreasonable policeman seize person subject limited search weapons unless probable cause arrest addressing question noted dealing entire rubric police conduct necessarily swift action predicated upon observations officer beat historically practical matter subjected warrant procedure result conduct involved case tested fourth amendment general proscription unreasonable searches seizures ibid omitted inquiry reasonableness conduct issue based balancing need search seize invasion search seizure entails quoting camara municipal concluded officer conduct reasonable stated holding follows merely hold today police officer observes unusual conduct leads reasonably conclude light experience criminal activity may afoot persons dealing may armed presently dangerous course investigating behavior identifies policeman makes reasonable inquiries nothing initial stages encounter serves dispel reasonable fear others safety entitled protection others area conduct carefully limited search outer clothing persons attempt discover weapons might used assault relied terry adams holding officer observations lead reasonably suspect particular vehicle may contain aliens illegally country may stop car briefly investigate circumstances provoke suspicion based relaxation traditional requirement importance governmental interest stemming flow illegal aliens minimal intrusion brief stop absence practical alternatives policing border ibid noted limited holdings terry adams authorizing police question driver passengers citizenship immigration status ask explain suspicious circumstances expressly stated detention search must based consent probable cause see also ybarra illinois terry case created exception requirement probable cause exception whose narrow scope careful maintain omitted dunaway new york discussing narrow scope terry progeny clear terry cases followed permit brief investigative stops extremely limited searches based reasonable suspicion provide police commission employ whatever investigative techniques deem appropriate stated florida royer scope investigative stop attendant search must extremely limited terry exception swallow general rule fourth amendment seizures searches reasonable based probable cause concurring result quoting dunaway new york supra ii respects opinion case seen logical successor plurality opinion florida royer supra plurality opinion royer contained considerable language unnecessary judgment brennan concurring result regarding permissible scope terry investigative stops see even assuming however finds support royer discussion scope terry stops today goes well beyond royer endorsing notion principles terry permit warrantless seizures personal luggage custody owner basis less probable cause purpose pursuing limited course investigation short opening luggage quickly confirm dispel authorities suspicion ante see also ante addition unnecessary judgment see supra suggestion finds support terry progeny significantly dilutes fourth amendment protections government interference personal property short represents radical departure settled fourth amendment principles noted supra terry cases followed authorize brief investigative stop individual based reasonable suspicion limited search weapons officer reasonably suspects individual armed presently dangerous purpose brief stop determine individual identity maintain status quo momentarily obtaining information adams williams anything brief stop must based consent probable cause supra course stop suspect must moved asked move short distance physical searches permitted extent necessary protect police officers involved encounter importantly suspect must free leave short time decline answer questions put kolender lawson brennan concurring true terry stops may involve seizures personal effects incidental seizure person involved obviously officer seize person without also seizing personal effects individual possession time difference incidental seizures personal effects seizures property independent seizure person fourth amendment protects effects well people unreasonable searches seizures regard justice stevens pointed texas brown fourth amendment protects two different interests citizen interest retaining possession property interest maintaining personal privacy opinion concurring judgment seizure threatens former search latter ibid even item searched therefore seizure implicates protected fourth amendment interest reason seizures property must based probable cause see colorado bannister payton new york leasing chambers maroney warden hayden see also texas brown supra stevens concurring judgment neither terry progeny changed rule case officers seizure respondent later independent seizure luggage implicated separate fourth amendment interests first respondent protected interest maintaining personal security privacy terry allows interest overcome authorizes limited intrusion officers reason suspect criminal activity afoot second respondent protected interest retaining possession personal effects terry may authorize seizures personal effects incident lawful seizure person nothing terry line cases authorizes police seizure personal property luggage independent seizure person seizures significantly expand scope terry stop may effected less probable cause obviously also significantly expand scope intrusion officers develop probable cause arrest respondent encounter see therefore let go despite absence probable cause arrest respondent officers seized luggage deprived possession respondent therefore subjected invasion personal security privacy also independent dispossession personal effects based simply reasonable suspicion difficult understand intrusion severe brief stop questioning even limited patdown search weapons view soon officers seized respondent luggage independent seizure exceeded scope permissible terry stop violated respondent fourth amendment rights addition officers seizure respondent luggage violated established rule seizures personal effects must based probable cause actions therefore upheld acknowledges seizures personal property must based probable cause see ante despite recognition employs balancing test drawn terry conclude personal effects may seized based reasonable suspicion see ante dunaway new york stated narrow intrusions involved terry progeny judged balancing test rather general principle fourth amendment seizures must supported standards probable cause intrusions fell far short kind intrusion associated arrest dunaway suggests use balancing test case inappropriate first intrusion involved case longer narrow one contemplated terry line cases see supra addition intrusion involved case involves seizure person also seizure property noted supra terry progeny address seizures property cases left unchanged rule seizures property must based probable cause see supra terry balancing test wrenched factual conceptual moorings important reasons balancing inquiries conducted except limited circumstances terry cases followed established isolated exceptions general rule fourth amendment already performed constitutional balance police objectives personal privacy michigan summers stewart dissenting protections intended framers easily disappear consideration balancing multifarious circumstances presented different cases especially balancing may done first instance police officers engaged often competitive enterprise ferreting crime dunaway new york supra quoting johnson truth proposition apparent one considers today employed balancing test swallow general rule seizures property reasonable based probable cause justice blackmun concern emerging tendency part convert terry decision general statement fourth amendment requires seizure reasonable post blackmun concurring judgment omitted certainly justified iii also suggests today discussion unnecessary judgment exposure respondent luggage narcotics detection dog constitute search within meaning fourth amendment ante district respondent contest validity sniff searches per se supp edny appeals reach discuss issue briefed argued short agree justice blackmun address issue see post blackmun concurring judgment also agree justice blackmun suggestion issue complex discussion lead one believe justice stevens suggested objecting unnecessarily broad dicta knotts use electronic detection techniques enhance human perception implicates especially sensitive concerns opinion concurring judgment obviously narcotics detection dog electronic detection device unlike electronic beeper knotts however dog merely allow police efficiently using senses dog adds new previously unobtainable dimension human perception use dogs therefore represents greater intrusion individual privacy use implicates concerns least sensitive implicated use certain electronic detection devices cf katz expressed view dog sniffs people constitute searches see doe renfrow brennan dissenting denial certiorari doe suggested sniffs inanimate objects might present different case event leave determination whether dog sniffs luggage amount searches subsidiary question standards govern intrusions future case providing appropriate informed basis deciding questions iv justice douglas dissenter terry stated powerful hydraulic pressures throughout history bear heavily water constitutional guarantees give police upper hand dissenting opinion today uses terry justification submitting pressures strength apparent even finds individual fourth amendment rights violated resist temptation weaken protections amendment affords seizure issue terry ohio actual physical restraint imposed suspect assumed officer initial approach questioning suspect amount seizure acknowledged however seizures may occur irrespective imposition actual physical restraint stated must recognized whenever police officer accosts individual restrains freedom walk away seized person see also standard however easier state apply compare mendenhall opinion stewart florida royer brennan concurring result stops usually consume minute michigan summers relied terry progeny hold warrant search contraband founded probable cause implicitly carries limited authority detain occupants premises proper search conducted footnotes omitted also relied terry pennsylvania mimms uphold officer order individual get car following lawful stop vehicle summers mimms focused seizures people putting aside legality independent seizure luggage correctly points seizure luggage effectively restrain person beyond initial stop since subjected possible disruption travel plans order remain luggage arrange return ante omitted extent relies van leeuwen support conclusion see ante reliance misplaced points holding van leeuwen expressly limited facts case ante moreover appeals adequately distinguished van leeuwen see stated unlike dispossession hand baggage passenger custody constitutes substantial intrusion mere detention mail custody control amounts minimal technical interference person effects resulting personal deprivation ibid justice blackmun justice marshall joins concurring judgment analysis part iii opinion quite sufficient support judgment agree facts case detention place luggage amounted functionally identical seizure person concern opinion general discussion part ii seizures luggage terry ohio exception warrant requirements haste resolve issue providing guidance courts often include opinions material technically constitutes dictum fault desire set guidelines terry seizures luggage based reasonable suspicion concerned however appears emerging tendency part convert terry decision general statement fourth amendment requires seizure reasonable pointed dissent florida royer prior cases suggest evaluation seizures fourth amendment amendment generally prohibits seizure unless pursuant judicial warrant issued upon probable cause particularly describing items seized see ante florida royer dissenting opinion correctly observes warrant may dispensed officer probable cause exception warrant requirement exigent circumstances applicable ante fourth amendment speaks terms freedom unreasonable seizures amendment leave reasonableness seizures judgment courts government officers framers amendment balanced interests involved decided seizure reasonable supported judicial warrant based probable cause see texas brown powell concurring rabinowitz frankfurter dissenting terry ohio however teaches circumstances limited seizure less restrictive formal arrest may constitutionally occur upon mere reasonable suspicion supported special law enforcement need greater flexibility florida royer dissenting opinion see michigan summers exception fourth amendment warrant requirements applicable reviewing must balance individual interest privacy government law enforcement interest determine whether seizure reasonable circumstances limited context entitled engage balancing interests determining validity seizure agree significant law enforcement interest interdicting illegal drug traffic nation airports ante see florida royer dissenting opinion limited intrusion caused temporary seizure luggage investigative purposes fall within terry exception critical threshold issue intrusiveness seizure case seizure went well beyond minimal intrusion therefore fall within terry exception ii resolution status dog sniffs fourth amendment troubling different reason district expressly observed place contest validity sniff searches per se supp edny place may possessed claim chose raise issue also presented decided appeals moreover contrary apparent intimation ante answer question necessary decision purposes case precise nature legitimate investigative activity irrelevant regardless validity dog sniff fourth amendment seizure intrusive need decide issue matter prudence decision issue also unwise adopted one plausible analysis issue others example dog sniff may search minimally intrusive one justified situation terry upon mere reasonable suspicion neither party opportunity brief issue grasps appropriate analysis problem although essential ever adopt views one parties decide issue neither party expressed opinion certainly position consider ramifications important issue certiorari currently pending two cases present issue directly beale waltzer reason avoid full airing issue proper case foregoing reasons concur judgment applicability terry exception rests balancing competing interests determine reasonableness type seizure involved within meaning fourth amendment general proscription unreasonable searches seizures ante quoting terry context quotation terry makes clear however balancing determine reasonableness occurs exceptional circumstances justify terry exception deal entire rubric police conduct necessarily swift action predicated upon observations officer beat historically practical matter subjected warrant procedure instead conduct involved case must tested fourth amendment general proscription unreasonable searches seizures ibid agree assertion diligence police acting suspicion relevant extent intrusion fourth amendment interests see ante makes little difference traveler whose luggage seized whether police conscientiously followed lead bungled investigation duration intrusiveness seizure altered diligence police exercise course diligence may relevant determination reasonableness seizure determined seizure sufficiently nonintrusive eligible terry exception district hold dog sniff conducted fashion circumstances reasonably calculated achieve tainted reaction dog however due process claim one fourth amendment place apparently raise issue appeals