Thursday's debate on the conduct of Lord Lester of Herne Hill is not going to be a formality.
The Lords Privileges and Conduct Committee wants him suspended from the House until 3 June 2022, after accepting complaints against him of sexual harassment, and offering a complainant "corrupt inducements" to sleep with him, in the form of a promise of a peerage.
The original recommendation had been that Lord Lester should be expelled, for what the committee regarded as "a grave abuse of power".
This was reduced to a long suspension on the argument that expulsion was not possible when the behaviour occurred, 12 years ago.
Lord Lester continues to deny the complaint and says the investigation was "seriously flawed".
Peers are due to vote on whether or not to accept the recommended suspension on Thursday.
Motions of this kind are amendable, so it would be open to the House to reduce, or increase this punishment, but it has never happened.
But now, the Crossbench peer and leading QC, Lord Pannick, one of the most influential members of the Lords, has put down an amendment.
He wants to send the report back to the Privileges and Conduct Committee, arguing that the Commissioner for Standards, who investigates complaints, had failed to "act in accordance with the principles of natural justice and fairness".
Lord Pannick, a close friend and colleague of Lord Lester for nearly 40 years, said that it is impossible fairly and effectively to decide on the truth of allegations of sexual harassment said to have occurred nearly 12 years ago, without allowing for the cross-examination of the complainant.
The Commissioner refused to allow Lord Lester to cross-examine and the Commissioner failed herself to carry out that function, or appoint an independent QC to cross examine.
"Such a process would not be acceptable in any other regulatory, disciplinary or employment context. Parliament has applied a procedure that would be invalidated by the courts if Lord Lester were to be suspended by his local darts club," Lord Pannick said.
So to be clear, this is an argument about whether there was a fair process to establish Lord Lester's guilt.
In the past, Lord Pannick has been a decisive voice in swinging Lords debates and votes, but there is no precedent for amending motions of this kind.
So watch this space.