Home Secretary Theresa May aims to make sure that police officers always have "reasonable suspicion" before they stop anyone in England or Wales.
Her Best Use of Stop and Search Scheme does not apply in Scotland, where officers can carry out a consensual search without suspicion.
However, Lib Dem Justice spokeswoman Alison McInnes said: "Kenny MacAskill's stubborn refusal to tackle the unregulated nature of stop and search has resulted in Scotland falling further behind England and Wales in its efforts to protect civil liberties.
"Scots are already seven times more likely to be stopped and searched by police than people in England and Wales. Three quarters of stop and searches in Scotland lack sound legal basis, intelligence or suspicion."
Scottish police have long argued that such "voluntary" searches are a useful tool in fighting crime.
Numbers of stop and searches carried out have soared in recent years but are now dipping again, according to the most recent figures.