Unionist politicians will be unable to re-instate the old 11-plus transfer test, even if they take the education ministry after May's Assembly election, Sinn Fein has claimed.
The party's Assembly group leader John O'Dowd said laws framing the exam system have lapsed, meaning a future unionist minister would need Sinn Fein support in the Assembly to pass fresh legislation on the test.
Department of Education sources have also confirmed that a return to the pre-existing government-sponsored 11-plus system would require fresh legislation from MLAs.
In the event of unionists seizing the education portfolio, they would no doubt seek other tactics to deliver their policy goals, just as Sinn Fein education minister Caitriona Ruane has done during her term in office.
But Mr O'Dowd said: "A unionist party could change the guidance issued by the minister.
"But to bring back state-sponsored testing, I understand you would require fresh legislation, which means you would need agreement at the Assembly - which is where we are now."
Despite the continuing divisions over the issue, Mr O'Dowd said republicans had no regrets over their battle to end academic selection.
"All in all, what we did over this last three and a half years had to be done the way it was done," he said.
"You could look at the small time-frame we have been in power, but there has been a five-decade debate on academic selection.
"If you look at the 1989 DUP election manifesto, it states that the test is socially divisive.
"But every time selection came close to being ended, the grammar lobby fought back and won.
"This lobby group was able to send the DUP to St Andrews to negotiate around the 11-plus.
"What other sector could do that? Could the farming sector, could the business sector? I doubt it. So those are the sort of forces we were against."
The issue of academic selection split the Assembly, with all parties effectively uniting against Sinn Fein's determination to scrap the test when republicans knew the DUP would oppose fresh legislation to put new transfer mechanisms in place.
Ms Ruane opted instead to use her power to issue guidance to schools, aimed at steering the education sector away from testing to select children for second level schools.
The result was that state-controlled and Catholic-maintained grammars introduced their own tests, though the Catholic sector may have started the process of moving away from testing.
But Mr O'Dowd said despite the criticism heaped on his party over the issue, he believed Sinn Fein had sparked a debate within both the state and Catholic sectors.
"When people say Sinn Fein took a hammering over academic selection, I get the sense that unionist parties have taken a hammering over it in two directions," he said.
"From the grammar lobby who said, 'I thought you were protecting us on this and you haven't'.
"And from others from the controlled post-primary sector, saying, 'what about us, we have a voice and a raison d'etre in terms of education too'.
"Political unionism has taken a hit over that."
He added: "People opposed to academic selection needed to be able to see that someone was willing to take a stand and willing to take action. We took a stand."