ibp alvarez individually behalf others similarly situated et argued october decided november ruled term workweek fair labor standards act flsa included time employees spent walking time clocks near factory entrance workstations anderson mt clemens pottery congress passed act inter alia excepted flsa coverage walking employer premises location employee principal activity activities activities preliminary postliminary said principal activity activities act otherwise change descriptions work workweek define workday regulations promulgated secretary labor shortly thereafter concluded act affect computation hours within workday cfr includes period commencement completion principal activity activities eight years enactment act interpretative regulations explained term activity activities embraces activities integral indispensable part principal activities including donning doffing specialized protective gear regular work shift production line steiner mitchell respondent employees filed class action seeking compensation time spent donning doffing required protective gear walking locker rooms production floor meat processing facility owned petitioner ibp ibp back district found activities compensable ninth circuit affirmed petitioner employees sought compensation time spent donning doffing required protective gear poultry processing plant operated respondent barber foods barber well attendant walking waiting times barber prevailed walking waiting claims appeal first circuit found times preliminary postliminary activities excluded flsa coverage act held time respondents spend walking changing production areas compensable flsa pp section text exclude time flsa scope ibp claims donning principal activity starts workday walking occurring immediately donning immediately doffing compensable argument effect asks third category activities integral indispensable principal activity thus excluded coverage principal activities defined foreclosed steiner made clear remove activities integral indispensable principal activities flsa coverage precisely activities principal activities plausible argument terms mean different things normal rule statutory interpretation identical words used different parts statute generally presumed meaning reference said principal activity activities said explicit reference use identical term pp also unpersuasive ibp argument congress repudiation anderson holding reflects purpose exclude walking time issue time occurs workday begins ends comparable time spent walking two different positions assembly line walking anderson occurred workday began pp relevant regulations also support view walking contrary ibp claim cfr strictly define workday limits period whistle whistle provides postdonning walking time necessarily excluded scope mean time always excluded insufficient overcome clear statements regulations text support holding pp donning doffing gear integral indispensable employees work principal activity statute continuous workday rule mandates time petitioners spend walking production floor donning doffing well time spent waiting doff affected act instead covered flsa pp however excludes flsa scope time employees spend waiting first piece gear marks beginning continuous workday waiting two steps removed productive activity assembly line comfortably qualifies preliminary activity fact certain preshift activities necessary employees engage principal activities mean preshift activities integral indispensable principal activity steiner limiting principle allows conclude waiting time activity without also leading logical untenable conclusion walking time anderson also principal activity unaffected act title cfr support contrary view pp affirmed affirmed part reversed part remanded stevens delivered opinion unanimous ibp petitioner gabriel alvarez individually behalf others similarly situated et al writ certiorari appeals ninth circuit abdela tum et petitioners barber foods dba barber foods writ certiorari appeals first circuit november justice stevens delivered opinion consolidated cases raise questions concerning coverage fair labor standards act flsa amended act respect activities employees must protective clothing employer premises engage productive labor primarily hired principal question presented cases whether time employees spend walking changing area production area compensable flsa second question presented whether time employees spend waiting put protective gear compensable statute appeals ninth circuit answered yes first question appeals first circuit answered questions granted certiorari resolve conflict enacted flsa et required employers engaged production goods commerce pay employees minimum wage less cents hour stat prohibited employment person workweeks excess hours second year following legislation unless employee receives compensation employment excess hours rate less one times regular rate employed neither work workweek defined early cases defined terms broadly tennessee coal iron muscoda local held time spent traveling iron ore mine portals underground working areas compensable relying remedial purposes statute webster dictionary described work employment physical mental exertion whether burdensome controlled required employer pursued necessarily primarily benefit employer business see year armour wantock clarified exertion fact necessary activity constitute work flsa pointed employer chooses may hire man nothing nothing wait something happen two years later anderson mt clemens pottery defined statutory workweek include time employee necessarily required employer premises duty prescribed workplace accordingly held time necessarily spent employees walking time clocks near factory entrance gate workstations must treated part workweek year decision anderson congress passed act amending certain provisions flsa based findings judicial interpretations flsa superseded customs practices contracts employers employees thereby creating wholly unexpected liabilities immense amount retroactive operation stat responded two statutory remedies first relating existing claims second future claims remedies distinguish working time compensable pursuant contract custom practice one hand time found compensable expansive reading flsa like original flsa however act omits definition term work respect existing claims act provided employers incur liability account failure pay minimum wages overtime compensation activity compensable either express contract established custom respect future claims act preserved potential liability working time made compensable contract custom narrowed coverage flsa excepting two activities treated compensable cases walking employer premises actual place performance principal activity employee activities preliminary postliminary principal activity specifically part iii act entitled future claims provides relevant part sec relief certain future claims fair labor standards act except provided subsection covers work compensable contract custom employer shall subject liability punishment fair labor standards act amended account failure employer pay employee minimum wages pay employee overtime compensation account following activities employee engaged date enactment act walking riding traveling actual place performance principal activity activities employee employed perform activities preliminary postliminary said principal activity activities occur either prior time particular workday employee commences subsequent time particular workday ceases principal activity activities stat codified express exceptions travel location employee principal activity activities preliminary postliminary principal activity act purport change earlier descriptions terms work workweek define term workday regulation promulgated secretary labor shortly enactment concluded statute effect computation hours worked within workday regulation extent activities engaged employee occur employee commences perform first principal activity particular workday ceases performance last principal activity particular workday provisions application cfr similarly consistent prior decisions interpreting flsa department labor adopted continuous workday rule means workday generally defined period commencement completion workday employee principal activity activities regulations remained effect since see fed reg party disputes validity continuous workday rule eight years enactment act promulgation interpretive regulations confronted question whether workers battery plant statutory right compensation time incident changing clothes beginning shift showering end must make extensive use dangerously caustic toxic materials compelled circumstances including vital considerations health hygiene change clothes shower facilities state law requires employers provide steiner mitchell distinguishing changing clothes showering normal conditions stressing important health safety risks associated production batteries endorsed appeals conclusion activities compensable flsa reaching result specifically agreed appeals term activity activities section act embraces activities indispensable part principal activities activities question fall within category thus steiner activities donning doffing specialized protective gear performed either regular work shift production line compensable provisions fair labor standards act activities integral indispensable part principal activities covered workmen employed specifically excluded section principal question presented consolidated cases involve required protective gear courts found integral indispensable employees work whether postdonning predoffing walking time specifically excluded conclude ii petitioner ibp ibp large producer fresh beef pork related products plant pasco washington employs approximately workers job classifications slaughter division line workers job classifications processing division production workers divisions must wear outer garments hardhats hairnets earplugs gloves sleeves aprons leggings boots many particularly use knives must also wear variety protective equipment hands arms torsos legs gear includes chain link metal aprons vests plexiglass armguards special gloves ibp requires employees store equipment tools company locker rooms protective gear production workers pay based time spent cutting bagging meat pay begins first piece meat ends last piece meat since however ibp also paid four minutes changing respondents ibp employees filed class action recover compensation preproduction postproduction work including time spent donning doffing protective gear walking locker rooms production floor assigned shifts lengthy bench trial district eastern district washington held donning doffing protective gear unique jobs issue compensable flsa integral indispensable work employees wore equipment moreover consistent continuous workday rule district concluded employees required doff unique protective gear walking time locker room production floor also compensable occurs however allow recovery ordinary clothes changing washing donning doffing hard hat ear plugs safety glasses boots hairnet app pet cert district proceeded apply legal conclusions making detailed factual findings regard different groups employees example district found view covered flsa processing division knife users entitled compensation minutes preproduction postproduction work including minutes walking time appeals agreed district ultimate conclusions issues part different reasons noting question whether activities integral indispensable part principal within meaning steiner context specific appeals endorsed distinction burdensome donning doffing elaborate protective gear one hand time spent donning doffing nonunique gear hardhats safety goggles donning doffing nonunique gear categorically excluded principal activities defined act rather context case time employees spent donning doffing nonunique protective gear minimis matter law ibp challenge holding light steiner donning doffing unique protective gear principal activities act moreover ibp asked us overrule steiner considerations stare decisis particularly forceful area statutory construction especially unanimous interpretation statute accepted settled law several decades thus question us decide whether appeals correctly rejected ibp contention walking locker rooms production areas excluded flsa coverage act ibp argues text history purpose enactment department labor interpretive guidance compel conclusion act excludes walking time scope flsa find arguments unpersuasive text ibp correctly points decision steiner held donning doffing protective gear case activities integral indispensable workers principal activity making batteries ibp view category integral indispensable activities may compensable merely preliminary postliminary within meaning necessarily coextensive actual principal activities employee employed perform within meaning words ibp argues even though concluded donning doffing unique protective gear integral indispensable employees principal activity means donning doffing gear covered flsa according ibp donning principal activity starts workday walking occurs immediately donning immediately doffing compensable effect ibp asks us create third category activities integral indispensable principal activity thus excluded coverage principal activities term defined ibp submission foreclosed steiner noted steiner made clear act remove activities flsa coverage precisely activities principal activities steiner specifically addressed proper interpretation term principal activity activities plausible argument terms mean something different normal rule statutory interpretation identical words used different parts statute generally presumed meaning sullivan stroop also refers said principal activity activities stat emphasis added said explicit reference use identical term indeed ibp offered support unlikely proposition congress intended create intermediate category activities sufficiently principal compensable sufficiently principal commence workday accepting necessary import holding steiner conclude locker rooms special safety gear donned doffed relevant place performance principal activity employee employed perform within meaning walking place starting work excluded flsa coverage statutory text exclude walking place another area within plant immediately workday commenced purpose ibp emphasizes decision anderson mt clemens pottery may well proximate cause enactment act case held flsa mandated compensation time employees spent walking time clocks located near plant entrance respective places work prior start productive labor ibp view congress forceful repudiation holding reflects purpose exclude ibp regards quite similar walking time spent respondents work slaughtering cattle processing meat even ambiguity statute construe effectuate important purpose argument also unpersuasive critical difference walking issue anderson walking issue case anderson walking preceded employees principal activity occurred workday began relevant walking case occurs workday begins ends endorse ibp novel submission activity sufficiently principal compensable sufficiently start workday case comparable anderson moreover significant difference potentially expansive liability might result rule treated travel workday begins compensable rule issue case indeed processing division knife users largest segment work force ibp plant walking time dispute consumes less time donning doffing activities precede follow comparable time spent walking two different positions assembly line prework walking anderson regulations regulations adopted secretary labor support respondents view donning doffing protective gear compensable activities may also define outer limits workday regulations minutes spent walking locker rooms production area similar time spent walking two different workplaces disassembly line see cfr explaining act affect compensability time spent traveling place performance one principal activity another see also explaining later regulation interpreting flsa employee required report meeting place receive instructions perform work pick carry tools travel designated place work place part day work must counted hours worked ibp argues however two provisions regulations point different conclusion use phrase whistle whistle discussing limits workday stating postchanging walking time necessarily excluded scope whistle whistle reference reflect view situations workday defined beginning ending primary productive activity relevant text describes workday roughly period whistle whistle emphasis added indeed next subsection regulation used portal act means general period commencement completion workday employee principal activity activities ibp emphasis whistle whistle reference unavailing ibp relies washing work like changing clothes may certain situations directly related specific work employee employed perform regarded integral part employee activity necessarily mean however travel washroom place actual place performance specific work employee employed perform excluded type travel section refers emphasis added citations omitted indicate secretary assumed cases walking locker room employee performs first principal activity production line covered flsa cases assumption course inconsistent ibp submission walking always excluded inconsistent respondents view walking never excluded whatever correct explanation secretary ambiguous apparently ambivalent statement may sufficient overcome clear statements text regulations support holding surely sufficient overcome statute whose meaning definitively resolved steiner foregoing reasons hold activity integral indispensable principal activity principal activity act moreover continuous workday walking time occurs beginning employee first principal activity end employee last principal activity excluded scope provision result covered flsa iii respondent barber foods barber operates poultry processing plant portland maine employs production workers employees operate six production lines perform variety tasks require different combinations protective clothing paid hour time punch computerized time clocks located entrances production floor petitioners barber employees former employees brought action recover compensation alleged unrecorded work covered flsa specifically claimed barber failure compensate donning doffing required protective gear attendant walking waiting violated statute extensive discovery magistrate judge issued comprehensive opinion analyzing facts detail recommending entry partial summary judgment favor barber opinion later adopted district maine included two critical rulings first magistrate held donning doffing clothing equipment required defendant government regulation opposed clothing equipment employees choose wear use option integral part plaintiffs work therefore excluded compensation act preliminary postliminary activities app pet cert pp second magistrate rejected petitioners claims compensation time spent obtaining clothing equipment time magistrate view reasonably construed integral part employees work activities walking cage hairnets earplugs dispensed ibid accordingly barber entitled summary judgment claims based time spent walking plant entrances employee workstation locker time clock site clothing equipment required worn job obtained claims based time spent waiting punch clothing equipment magistrate judge opinion specifically address question whether walking time production line place donning doffing encompassed act thus excluded coverage flsa whatever intended scope magistrate grant partial summary judgment questions submitted jury trial asked jurors consider whether barber required compensate petitioners time spent actually donning doffing various gear case submitted jury parties stipulated four categories workers rotating meatroom shipping receiving associates required protective gear beginning shifts required doff gear end shifts jury made factual findings regard amount time reasonably required category employees doff items jury concluded time de minimis therefore compensable jury concluded two categories employees maintenance sanitation associates required protective gear starting accordingly jury ruled barber counts appeal petitioners argued among things district improperly excluded noncompensable time employees spend walking production floor donning required safety gear time spend walking production floor area doff gear appeals rejected petitioners argument concluding walking time species preliminary postliminary activity excluded flsa coverage act explained discussion ibp submission see part ii supra categorical conclusion incorrect petitioners also argued appeals waiting time associated donning doffing clothes compensable appeals disagreed holding waiting time qualified preliminary postliminary activity thus excluded flsa coverage act analysis part ii supra demonstrates appeals incorrect regard predoffing waiting time doffing gear integral indispensable employees work principal activity statute continuous workday rule mandates time spent waiting doff affected act instead covered flsa time spent waiting time elapses principal activity donning integral indispensable gear presents quite different question whether effect advancing time workday begins barber argues predonning waiting time explicitly covered act noted excludes activities preliminary postliminary principal activity activities scope flsa contrast petitioners supported amicus curiae maintain predonning waiting time integral indispensable principal activity donning therefore principal activity however unlike donning certain types protective gear always essential worker job waiting may may necessary particular situations every employee certainly integral indispensable sense donning however always comfortably qualify preliminary activity thus agree petitioners predonning waiting time issue case principal activity barber points fact certain preshift activities necessary employees engage principal activities mean preshift activities integral indispensable principal activity steiner example walking time clock near factory gate workstation certainly necessary employees begin work indisputable act evinces congress intent repudiate anderson holding walking time compensable flsa discern limiting principle allow us conclude waiting time dispute principal activity without also leading logical untenable conclusion walking time issue anderson principal activity thus unaffected act government also relies regulation promulgated secretary labor supporting petitioners view regulation cfr employee required employer report particular hour workbench place performs principal activity employee hour ready willing work reason beyond control work perform time elapsed waiting work integral part employee principal activities regulation applicable barber required workers report changing area specific time find protective gear available time elapsed evidence record case pertinent believe portion characterizes time employees must spend waiting check waiting receive paychecks generally preliminary activity covered act see regulation fully consistent statutory provisions allow compensability collateral activities depend either agreement parties custom practice particular industry short persuaded waiting case two steps removed productive activity assembly line integral indispensable principal activity identifies time continuous workday begins accordingly hold excludes scope flsa time employees spend waiting first piece gear marks beginning continuous workday iv reasons stated affirm judgment appeals ninth circuit affirm part reverse part judgment appeals first circuit remand case proceedings consistent opinion ordered footnotes together tum et al barber foods dba barber foods certiorari appeals first circuit footnotes pertinent definition provides includes suffer permit work stat part ii act entitled existing claims relevant part sec relief certain existing claims fair labor standards act employer shall subject liability punishment fair labor standards act action proceeding commenced prior date enactment act account failure employer pay employee minimum wages pay employee overtime compensation account activity employee engaged prior date enactment act except activity compensable either express provision written nonwritten contract effect time activity employee agent representative employer custom practice effect time activity establishment place employee employed covering activity inconsistent written nonwritten contract effect time activity employee agent representative employer stat codified regulation provides full section portal act affect computation hours worked within proper roughly described period whistle whistle provisions nothing compensability fair labor standards act activities engaged employee period provisions section one conditions must present activities excluded hours worked either prior time particular workday employee commences subsequent time particular workday ceases principal activity activities employed perform accordingly extent activities engaged employee occur employee commences perform first principal activity particular workday ceases performance last principal activity particular workday provisions section application periods time commencement employee first principal activity completion last principal activity workday must included computation hours worked extent required portal act enacted principles determining hours worked within proper continue established fair labor standards act without reference portal act concerned question relates time spent outside activities kind described section footnotes omitted ibp contend time fully compensated respondents preproduction postproduction time issue case district explained walking time compensable occurs start workday walking time excluded portal portal act occurs prior time particular work day employee commences subsequent time particular work day ceases principal activity activities id work day begins commencement employer principal activity activities ends completion employee activity app pet cert pp fact noted steiner specifically endorsed view appeals definition principal activity activities encompassed activities principal activities make distinction claims brought workers longer part case explained analysis different barber required employees arrive particular time order begin waiting