ent ▁and ▁a ▁design ▁pat ent , ▁granted ▁in ▁ 1 9 5 7 , ▁on ▁the ▁pole ▁lamp , ▁and ▁the ▁lamp ▁proved ▁a ▁" dec ided ▁commercial ▁success ," ▁according ▁to ▁the ▁Supreme ▁Court ' s ▁opinion . ▁ ▁So on ▁after ▁St iff el ▁brought ▁the ▁pole ▁lamp ▁to ▁market , ▁the ▁S ears , ▁Ro eb uck ▁& ▁Co . ▁department ▁store ▁put ▁on ▁the ▁market ▁copies ▁of ▁the ▁lamp . ▁St iff el ▁Co . ▁brought ▁suit ▁against ▁S ears , ▁for ▁pat ent ▁in fr ing ement ▁and ▁for ▁unf air ▁competition ▁under ▁Illinois ▁law , ▁the ▁latter ▁claim ▁based ▁on ▁S ears ' ▁alleg edly ▁causing ▁confusion ▁in ▁the ▁trade ▁as ▁to ▁the ▁source ▁of ▁the ▁l amps . ▁ ▁The ▁United ▁States ▁District ▁Court ▁for ▁the ▁Northern ▁District ▁of ▁Illinois , ▁held ▁the ▁pat ents ▁invalid ▁for ▁" w ant ▁of ▁in vention ," ▁but ▁ruled ▁S ears ▁to ▁be ▁guilty ▁of ▁unf air ▁competition ▁because ▁the ▁l amps ▁were ▁" conf using ly ▁similar ," ▁enjo ined ▁S ears ▁from ▁s elling ▁the ▁identical ▁l amps , ▁and ▁ordered ▁an ▁award ▁of ▁mon et ary ▁dam ages ▁to ▁St iff el ▁Co . ▁ ▁The ▁United ▁States ▁Court ▁of ▁App e als ▁for ▁the ▁Se vent h ▁Circ uit ▁aff ir med , ▁holding ▁that ▁under ▁Illinois ▁law , ▁St iff el ▁had ▁only ▁to ▁prove ▁that ▁there ▁was ▁a ▁" lik elihood ▁of ▁confusion ▁as ▁to ▁the ▁source ▁of ▁the ▁products " ▁due