A senator from Italy's anti-establishment Five Star Movement (M5S) has accused the party of denying his constitutional right to free speech, after he was expelled for appearing on TV talk shows.
M5S took Italian politics by storm in the February election, unexpectedly winning around a quarter of the vote.
Senator Marino Mastrangeli reacted furiously after he was ejected from the party on the grounds of breaking the movement's code of conduct for its MPs, which bans them from appearing on political chat shows.
"It's a disgrace. What's happening is an attack on articles 21 and 67 of the constitution," said Mr Mastrangeli, one of the wave of M5S candidates voted into parliament in the election. His comments were widely broadcast in the Italian media.
"I did some [TV] interviews, like all senators do. We're not in North Korea, after all. A parliamentarian who can't speak, what kind of a parliamentarian is that?" he said.
Mr Mastrangeli has since asked for an urgent meeting with the Speaker of the Italian Senate, Pietro Grasso, to discuss his "shameful" treatment.
He has even taken to appearing on TV with a copy of the constitution in hand, reading out passages defending his right to freedom of expression.
Five Star Movement leader Beppe Grillo, a former comedian, has a long-standing aversion to appearing in the Italian mainstream media, which he regards as a rotten branch of a corrupt political establishment that has failed the nation.
Since the movement's election success Mr Grillo has kept his distance from domestic media, preferring to use his blog and interviews with foreign media to convey his views.
He has particular scorn for the culture of TV talk shows, which are numerous, widely watched, and a mainstay of Italian political discourse.
The Five Star Movement's Code of Conduct for its MPs stipulates, among other things, that the official channel for party communication is the movement's website, and that MPs must "abstain from taking part in TV talk shows".
Italian media commonly refer to the ban as Mr Grillo's "fatwa" against TV shows.
The Five Star leader caused a furore and sparked accusations of sexism in 2012 when, having ticked off a female M5S councillor for going on a talk show, he likened the attraction of television to "the G-spot, which gives you an orgasm in talk-show studios".
Mr Grillo announced Marino Mastrangeli's expulsion via his website on 30 April, saying the final decision had been taken by an online vote of subscribers to his own blog.
"Senator Marino Mastrangeli has on numerous occasions violated the 'abstain from taking part in TV talk shows' rule, without seeking any co-ordination with the parliamentary grouping and thus damaging the image of the M5S by expressing his personal views," Mr Grillo wrote.
The Five Star Movement's parliamentary group had already taken a vote on 22 April in favour of the senator's expulsion.
Mr Mastrangeli has vowed to defy the move against him, which he rejected as "invalid and illegitimate". His lawyers were pursuing all legal avenues to challenge and overturn the decision, he said.
"They will have to physically remove me from the group's benches, because I'm not leaving the M5S," he added.