More than 80 lawyers have signed an open letter to Immigration Minister Jason Kenney challenging his insistence he played no role in granting Conrad Black a permit to live in this country even before the U.K. citizen had finished his jail time in Florida.

The lawyers, all immigration specialists, say they believe Mr. Kenney must have had some part in the controversial decision to grant a temporary resident permit to Mr. Black, who renounced his Canadian citizenship in pursuit of a British peerage and had served time in a Florida jail for fraud and obstruction of justice.

They are also daring the Harper government minister to haul them before the Law Society of Upper Canada for saying so.

Story continues below advertisement

The lawyers banded together in defence of Toronto colleague Guidy Mamann, whom Mr. Kenney's office tried to have censured after he told journalists that he found it improbable that such a major decision was made without the minister's input.

An aide to the Immigration Minister pursued a formal complaint against Mr. Mamann with the Law Society of Upper Canada this spring – which it dismissed in July. The body regulates the conduct of lawyers in Ontario.

On Wednesday, the lawyers wrote Mr. Kenney saying that they agree with Mr. Mamann's remark that "it was not credible" that the decision on Mr. Black was made "without any input from yourself."

"If you believe that our statement violates the Law Society of Upper Canada rules, please feel free to report us to the Law Society," the letter reads.

"We find the attempt by you and your officials to muzzle freedom of expression to be reprehensible. We will not succumb."

Mr. Kenney's office dismissed the letter.

"If the lawyers who signed this letter think it is acceptable for a lawyer to accuse a public office holder of interference without a shred of evidence, and with all evidence to the contrary, then, with due respect, they have a warped sense of professionalism and legal ethics," said spokeswoman Ana Curic.

Story continues below advertisement

Mr. Kenney had tried to lay the question to rest this spring, when Mr. Black obtained a temporary residence permit while he was still in a U.S. jail.

Ms. Curic said on Wednesday Mr. Kenney's office referred Lorne Waldman, a lawyer who gathered signatures for the letter, to documents it feels back up the minister's statements.

"We gave him the opportunity to review documents that contradict his and Mr. Mamann's false accusations. Unfortunately, rather than review the evidence and pursue the truth as one would expect from a lawyer, he chose the path of shameless self-promotion and public spectacle," she said.

When the news of Mr. Black's return broke in late April, the Immigration Minister said "highly trained" public servants made the decision. Mr. Kenney told reporters that when he learned of the application in February, he instructed immigration officials to handle it.

Mr. Mamann, a veteran Toronto immigration lawyer, told reporters he didn't believe the minister would leave such a high-profile decision to civil servants. The federal immigration minister can intervene in such cases.

"The idea that the minister didn't wink or nod in favour of this thing is impossible to imagine," Mr. Mamann said in comments published in The Globe and Mail in early May.

Story continues below advertisement

Shortly afterward, Mr. Kenney's office proposed to the Law Society of Upper Canada that it investigate the Toronto lawyer for violating its code of conduct.

The law society said in July it found insufficient evidence to warrant an investigation into Mr. Mamann; it closed the file.

A lawyer for the law society ruled that the allegations against Mr. Mamann offered no evidence of "conduct unbecoming a barrister or solicitor" and said his right to freedom of expression should not be "overridden by what might be characterized as a minor regulatory contravention."

Mr. Kenney's office on Wednesday said the 80-plus lawyers challenging the minister are only hurting themselves.

"Baseless accusations of misconduct and reckless character smears, by someone holding himself out to be an expert, poison the public discourse and debase the legal profession," Ms. Curic said.

"Instead of engaging in kneejerk outbursts of blind solidarity, these lawyers might consider the long-term damage to their profession of elevating activism above professionalism."