Stormont ministers have been accused of lacking courage to oppose legislation in Northern Ireland designed to tackle human trafficking and prostitution.
Mr McCrea said: "Sooner or later the Assembly has to grow up; if a bill will make bad law we should oppose it regardless of how sensitive and emotive the topic is.
"To do otherwise is simply to waste taxpayers' money. If ever a bill highlighted the need for the Assembly to develop an official opposition, this is it.
"Everyone is, of course, opposed to human trafficking and sexual exploitation (but) a desire to be seen to be doing something should not result in the Assembly producing poor legislation.
"This bill is duplicating, badly researched, (but) will pass through the Assembly because Justice Minister David Ford and other parties of the Executive are not brave enough to oppose a bill on such an emotive issue," the Lagan Valley MLA added.
His criticism followed the Assembly debate in which DUP MLAs warned that strong legislation expected in the Irish Republic could make Northern Ireland a greater centre for human trafficking in future.
Paul Givan, chair of the Justice committee, said: "Should the Irish Republic proceed with what now seems to be its intention, Northern Ireland will be exploited by those involved in human trafficking and the sexual exploitation of women in the Republic of Ireland. They will just move their business here."
He was echoing the comment of DUP colleague William Humphrey who said it was clear the Dublin government intends to implement an all-party Oireachtas group report. "The problem will be dumped over the border in Northern Ireland because we will have failed to act," he said.
Their warning came as the human trafficking bill now goes on to detailed scrutiny and potential amendment in committee.
DUP chairman Lord Morrow, who has championed his cause for more than a year now, told MLAs: "I do not believe in magic wands or silver bullets – I live in the real world (but) I strongly believe (the bill) will help to improve Northern Ireland's response to the heinous crimes of human trafficking and slavery.
"We need to go forward and criminalise those who seek to purchase sexual services. Criminalising paying for sex would simplify the current law and make it easier to secure convictions that send a clear message to traffickers.
"It seeks to reduce demand for sexual services, a driver for human trafficking in our province.
"It is a vital measure if we are to effectively tackle human trafficking and exploitation," the Fermanagh and South Tyrone MLA added.
Other parties, however, voiced fears that the proposal to make it a criminal offence to pay for sexual services could force human trafficking further underground.
The SDLP's Patsy McGlone said: "...it is not clear whether the stated objective would be achieved".
STORY SO FAR
Lord Morrow's private members' bill has been consulted on during the last year. It is based on a 15-year-old Swedish law which criminalises anyone who pays for sex. Women's groups and law reform lobbyists have backed change. Campaigners in the Republic of Ireland are calling for similar changes. But some experts from Queen's University Belfast warned that criminalising sex work could do more harm than good, driving the practice underground. A total of 33 potential human trafficking victims in Northern Ireland were rescued in 2011/12.