The Education Minister Joe McHugh has said the new Leaving Certificate system could be open to a legal challenge.
It was confirmed earlier the written exams, due to start at the end of July, will not go ahead.
Students will instead be given a predicted grade by their school - and the Department of Education will finalise their result.
However there is also the option for pupils to sit the written exams at a later date.
Minister McHugh told The Hard Shoulder several factors moved him against the original exams.
"We started modelling the Leaving Cert with the health advice that we had in terms of social distancing.
"So we were looking at a Leaving Cert that would start in July [and] end in September.
"Looking at a Leaving Cert that would have one subject per day, papers of one and half hours - and it basically was not the traditional Leaving Cert.
"So we came to the conclusion that we wouldn't be able to put the Leaving Cert together that other years had since 1925".
"There is a legitimate expectation on the part of every single Leaving Cert student - their legitimate expectation was to have a Leaving Cert that was similar to the Leaving Cert last year and previous years.
"So when we couldn't meet that legitimate expectation, we had to make the decision do we stand back and do nothing - and everybody loses out in a year and you can't move from primary to post-primary and from crèche to primary?
"So the decision we had to make was to look at a system that's not perfect obviously - but also a system that will ensure that each and every one of these students will move on to the next part of their life journey".
He said while he received legal advice on the issue, it could still be open to a challenge.
"We've got extensive legal advice, a lot of questions were asked around this and I asked for this legal advice early on.
"That's why this deliberation has taken quite a while".
"The [Attorney-General] has outlined that we can have an alternative system other than the Leaving Cert, but there has to be compelling medical advice that doesn't facilitate the existing, traditional Leaving Cert going ahead."
"He also outlined as well that this new system potentially, like any new system that's set up for the first time, could be potentially open to legal challenge as well".
Main image: The Minister for Education and Skills Joe McHugh talking to the media in Government Buildings, Dublin as he announced the postponement of the 2020 Leaving Certificate. Photo: Leon Farrell/Photocall Ireland