A review by the Public Prosecution Service (PPS) has backed the decision not to charge anyone in relation to the funeral of senior republican Bobby Storey.
It involved re-examining the case against 24 Sinn Féin politicians investigated for a suspected breach of health regulations.
The original no prosecution decisions were made in March.
The review agreed that the case failed the evidence test.
The funeral of Mr Storey, 64, a former head of intelligence of the IRA, brought 2,000 mourners onto the streets of west Belfast in June 2020 at a time when Covid-19 restrictions were in place.
Deputy First Minister Michelle O'Neill was among them and was one of the politicians the Police Service of Northern Ireland (PSNI) recommended for prosecution.
But the PPS decided that unclear regulations and prior engagement between police and organisers of the funeral posed "an insurmountable difficulty" to bringing any successful prosecutions.
The internal review, which has taken about 10 weeks to conclude, involved a senior PPS lawyer who was not involved in the original decision, assisted by an outside senior counsel.
PPS senior assistant director Marianne O'Kane said: "Whilst I appreciate concerns that what occurred was at least against the spirit of the law and public health guidance, the potential for prosecutions can only be assessed in light of the criminal law in force at the particular point in time.
"I can understand how difficult it is for many to reconcile the crowd scenes captured so publicly at the funeral of Mr Storey with the outcome that no prosecutions are directed for any breach of the regulations," she added.
"The PPS can only commence a prosecution when there is a reasonable prospect of conviction, and that threshold was not reached in this case."
The director of public prosecutions, Stephen Herron, said Ms O'Kane had "independently conducted a fresh consideration" of the case.
He added: "Our independence and need for objectivity in decision-making does not mean that we cannot recognise the depth of public feeling and hurt.
"I recognise the sacrifices that have been made by many in seeking to adhere to the coronavirus regulations and public health guidance.
"Those sacrifices have been most painful for many families who faced restrictions when making funeral arrangements for a loved one.
"I hope people can take some comfort in having made an important contribution to curbing the spread of Covid-19."
Previously, DUP MP Ian Paisley indicated that, on behalf of a constituent, he had instructed solicitors to commence legal action over the non-prosecution decision.