A California court will determine whether a defamation suit filed by Crystal Castles songwriter Ethan Kath will proceed against the Toronto duo's former singer who publicly claimed he sexually abused her for years.

Kath seeks unspecified damages in documents filed in a Los Angeles Superior Court under his birth name Claudio Palmieri.

The document alleges that online accusations made by Alice Glass, whose real name is Margaret Osborn, destroyed Kath's reputation and caused him to cancel a North American tour worth more than US$300,000.

The case accuses Glass, as well as other unidentified parties, of breach of contract.

But Glass's lawyer says her client was exercising her First Amendment right to free speech in making her claims and was emboldened by the .MeToo movement.

Lawyer Vicki Grecko filed a motion to dismiss the case, which will be heard Feb. 23.

Kath has denied allegations of abuse. None of the allegations have been proven in court.

The dispute traces back to October, when Glass posted a lengthy online message to fans alleging she was abused by Kath.

She wrote on her website that Kath abused her dating back to when she was 15 and he was 25.

She alleges he was manipulative and controlling during a relationship in which he gave her drugs and alcohol and she endured non-consensual sex and physical and emotional abuse.

Kath, who filed suit in November 2017, is seeking compensation including unspecified general, special and punitive damages.

Toronto police said Monday that an investigation of Kath by the sex crimes unit is ongoing.