cy ▁that ▁surr ounds ▁it . ▁ ▁Mobile ▁ph ones ▁are ▁also ▁commonly ▁used ▁to ▁collect ▁location ▁data . ▁The ▁ge ographical ▁location ▁of ▁a ▁mobile ▁phone ▁( and ▁thus ▁the ▁person ▁carrying ▁it ) ▁can ▁be ▁determined ▁easily ▁even ▁when ▁the ▁phone ▁is ▁not ▁being ▁used , ▁using ▁a ▁technique ▁known ▁as ▁mult il ater ation ▁to ▁calculate ▁the ▁differences ▁in ▁time ▁for ▁a ▁signal ▁to ▁travel ▁from ▁the ▁cell ▁phone ▁to ▁each ▁of ▁several ▁cell ▁to wers ▁near ▁the ▁owner ▁of ▁the ▁phone . ▁The ▁leg ality ▁of ▁such ▁techniques ▁has ▁been ▁question ed ▁in ▁the ▁United ▁States , ▁in ▁particular ▁whether ▁a ▁court ▁war rant ▁is ▁required . ▁Records ▁for ▁one ▁car rier ▁alone ▁( S print ), ▁showed ▁that ▁in ▁a ▁given ▁year ▁federal ▁law ▁enfor cement ▁ag encies ▁requested ▁customer ▁location ▁data ▁ 8 ▁million ▁times . ▁ ▁In ▁response ▁to ▁customers ' ▁priv acy ▁concerns ▁in ▁the ▁post ▁Edward ▁Snow den ▁era , ▁Apple ' s ▁iPhone ▁ 6 ▁has ▁been ▁designed ▁to ▁dis rupt ▁investig ative ▁wire t apping ▁efforts . ▁The ▁phone ▁encrypt s ▁e - mail s , ▁contacts , ▁and ▁photos ▁with ▁a ▁code ▁generated ▁by ▁a ▁complex ▁mathematical ▁algorithm ▁that ▁is ▁unique ▁to ▁an ▁individual ▁phone , ▁and ▁is ▁in access ible ▁to ▁Apple . ▁The ▁encryption ▁feature ▁on ▁the ▁iPhone ▁ 6 ▁has ▁drawn ▁criticism ▁from ▁F BI ▁director ▁James ▁B . ▁Com ey ▁and ▁other ▁law ▁enfor cement ▁officials ▁since ▁even ▁law ful ▁requests ▁to ▁access ▁user ▁content ▁on ▁the