▁v . ▁U . S ., ▁ 1 7 5 ▁U . S . ▁ 2 1 1 ▁( 1 8 9 8 ). ▁ ▁A ▁number ▁of ▁cases ▁have ▁subsequently ▁raised ▁doub ts ▁about ▁the ▁valid ity ▁of ▁the ▁illegal ▁per ▁se ▁rule . ▁ ▁Under ▁modern ▁Ant it rust ▁theories , ▁the ▁tradition ally ▁illegal ▁per ▁se ▁categories ▁create ▁more ▁of ▁a ▁pres umption ▁of ▁un reason ab len ess . ▁ ▁The ▁court ▁carefully ▁narrow ed ▁the ▁per ▁se ▁treatment ▁and ▁began ▁issu ing ▁gu idel ines . ▁ ▁Cour ts ▁and ▁ag encies ▁seeking ▁to ▁apply ▁the ▁per ▁se ▁rule ▁must : ▁ ▁show ▁" the ▁practice ▁fa cially ▁appears ▁to ▁be ▁one ▁that ▁would ▁always ▁or ▁almost ▁always ▁tend ▁to ▁restrict ▁competition ▁and ▁decrease ▁output "; ▁ ▁show ▁that ▁the ▁practice ▁is ▁not ▁" one ▁designed ▁to ▁' in cre ase ▁economic ▁efficiency ▁and ▁render ▁mark ets ▁more , ▁rather ▁than ▁less , ▁compet itive ' "; ▁ ▁carefully ▁examine ▁market ▁conditions ; ▁and ▁ ▁absent ▁good ▁evidence ▁of ▁compet it iveness ▁behavior , ▁avoid ▁bro aden ing ▁per ▁se ▁treatment ▁to ▁new ▁or ▁innov ative ▁business ▁relationships . ▁ ▁See ▁also ▁ ▁Mal um ▁in ▁se ▁ ▁Neg lig ence ▁per ▁se ▁ ▁Pres umption ▁ ▁Rule ▁of ▁reason ▁ ▁Str ict ▁li ability ▁( c riminal ) ▁ ▁References ▁ ▁Category : Comp et ition ▁law ▁Category : American ▁legal ▁termin ology <0x0A> </s> ▁K D MT ▁may ▁refer ▁to : ▁ ▁K D MT ▁(