i believe they have to be ADR approved to be "legal" otherwise engineering cert done to prove that they improve the cars handling..

altho.. in some cases u can buy some coilovers i.e. tein SS which are ADR approved already..

BUT

i went with my friend one day to clear his defect and they said as long as the coil is held in correctly and the spring is captive then it should be ok??? but i have no idea.. but if yoru worried about getting defected then leave your car stock..