SINN Féin sent SDLP leader Colum Eastwood a letter threatening legal action over remarks he made last year.
The Foyle MP said he responded to Sinn Féin's legal team and that the matter is closed but says he believes that defamation laws are being used by some political parties to "scare off opponents".
Details of the solicitor's letter to the SDLP leader were revealed during his contribution to the Awkward Conversations podcast, recorded last week.
They came just days after it emerged that Sinn Féin leader Mary Lou McDonald is suing broadcaster RTÉ.
Mrs McDonald’s claim is understood to relate to a discussion on Morning Ireland in February during which reference was made to Sinn Féin's treatment of women who made allegations of sexual assault against members of the IRA.
Asked about politicians threatening legal action against media outlets, Mr Eastwood said: "The DUP have been very good at using the libel laws but I also know that Sinn Féin routinely send legal letters to opponents and to journalists – I know that because I received one of them."
He said he didn't go public about the legal threat at the time, dismissing it as "nonsense".
"Political debate used to be just that but now people are sending legal letters," he said.
"For me, I can send back a tough response and that was the end of the matter but I mean doing that to a journalists and other people who aren’t as fit to respond, it’s just no way of doing political debate."
Mr Eastwood told how he responded to Sinn Féin's legal representative by insisting any subsequent trial was held in front of a jury.
"I just informed them we’d be seeking a jury trial and also that there’d be a number of key witnesses, who they may have not wanted on the stand, called… and we’d see how that goes," he said.
"They should not be using libel laws to scare off opponents," the SDLP leader said.
Mr Eastwood said he couldn't recall whether the response was in writing or if "my solicitor spoke to their solicitor".
"It was one of the two – but I wasn’t going to be silenced," he said.
Sinn Féin was approached for comment.
