The government's decision to scrap the 11-plus school transfer exam could face a legal challenge.
Bob McCartney wants academic selection retained
A pro-grammar school organisation is launching a "fighting fund" with the aim of using human rights laws to derail changes to selection procedures.
QC Bob McCartney, who is supporting the move, said that Northern Ireland's education is under threat.
"This is without doubt the biggest issue that has faced Northern Ireland parents for 50 years," he said.
"Northern Ireland has the best A-level results in the United Kingdom.
"Northern Ireland sends 42.5% of its students to university from disadvantaged homes. The comprehensive system sends 28.2%," Mr McCartney added.
However, Sinn Fein's Michael Ferguson accused Mr McCartney of being involved in a "campaign of misinformation".
"The pro-grammar school lobby are peddling a lot of myths about the end of academic selection and the 11-plus.
"The fact is that there is no evidence that ending 11-plus will lead to the destruction of grammar schools," Mr Ferguson said.
SDLP education spokesman Dominic Bradley also said that grammar schools were not under threat.
"Pupils at age 14 will be able to choose a vocational or academic pathway or indeed a combination of both as best suits their educational needs and abilities," he said.
"There is no reason why current selective and non-selective schools should not continue to achieve the high standards which they have achieved up until now".
In January 2004, then education minister Jane Kennedy announced the government was abolishing academic selection in Northern Ireland.
The first move to remove the system was made by Stormont minister Martin McGuinness hours before he left office in October 2002.
The last 11-plus transfer test is scheduled to be in 2008.