Tanaiste Joan Burton has raised serious doubts over Sinn Fein's commitment to the rule of the law following Gerry Adams' reaction to the conviction of tax cheat and former IRA chief, Thomas 'Slab' Murphy.
Ms Burton and other senior politicians rounded on Mr Adams following his claims that Murphy has been "treated unfairly" and had his rights "denied".
The Labour Party leader said Mr Adams' reaction to the verdict of the Special Criminal Court on Thursday "speaks volumes" about his party's claims of being committed to democracy and the rule of law.
"Yet again, the mask has slipped and Sinn Fein have revealed how unsuitable they are for government," Ms Burton told the Herald.
"It seems to me that Sinn Fein will endorse action against their opponents but bitterly oppose anything that impacts on them.
"It's one rule of law for Sinn Fein and another for everyone else."
Fianna Fail leader Micheal Martin pointed out that the decision to try Murphy in the Special Criminal Court was dealt with through the legal system.
"He [Mr Adams] faces a simple question now - does he or does he not accept the authority and judgment of the Irish Supreme Court?" he said.
Justice Minister Frances Fitzgerald added: "Without commenting on a particular case, I can assure people that the gardai and other law enforcement agencies will continue to pursue crime whatever the background of those who commit it and irrespective of whom might purport to vouch for them."
Yesterday, Mr Adams launched a desperate attack on Mr Martin and the media in general for its reporting of the controversy.
"Let me be very clear, Sinn Fein is strongly opposed to tax evasion," he said in a statement.
"Everyone has a duty to pay their taxes and there can be no equivocation about this."
Mr Adams added that his party supports the gardai and the law, but he claimed that Murphy should have been tried before a jury.
"Let me be equally clear that Sinn Fein is absolutely opposed to the existence and operation of the non-jury Special Criminal Court," he said.
"As I have already remarked, there was nothing ordinary or routine about the trial and conviction of Tom Murphy.
"He was denied the right to be tried before a jury of his peers and this raises serious concerns."