It's now been claimed that four soldiers are to face prosecution, with the Public Prosecution Service due to meet the families of victims and make an announcement on March 14.
Dr Austen Morgan is a barrister in London and Belfast and the author of The Belfast Agreement: A Practical Legal Analysis (2000).
He said a number of factors made it unclear as to what punishment the soldiers could face.
The Good Friday Agreement included a clause that anyone convicted of a "scheduled offence" between 1973 and April 1998 would serve a maximum of two years in prison.
It had been widely assumed this only applied to members of terrorist organisations, but Dr Morgan said there was no reason this shouldn't also apply to members of the security forces.
As Bloody Sunday took place in 1972, however, he said the soldiers could not depend on this.
Defence Secretary Gavin Williamson is expected to bring forward legislation to protect soldiers, with a 10 year limit on prosecution for historic offences.
It's understood this would have to apply to terrorist offences as well.
"All bets are off," said Dr Morgan.
"Once you have partial and secret amnesties, the only way forward is for amnesties all round."
Either way, he said a successful prosecution was unlikely.
"Anything that was said in the Saville report has immunity and none of the soldiers are likely to admit any responsibility."
He added: "The security services have been far more organised in the last five years and quite a few MPs have a military background. So, at present, their idea of a legislative opt-out is very much on the table".