Kanye West's tour firm is suing Lloyd's of London for nearly $10m (£7.5m) over the cancellation of the rapper's concerts.
Very Good Touring said in legal papers filed with Los Angeles federal court on Tuesday that one of London's oldest insurance firms has refused to pay a claim.
The company alleges Lloyd's has implied it can refuse to pay out by claiming West's marijuana use is responsible for his medical condition.
West, 40, cancelled 21 dates of his Saint Pablo tour last year with a promise that tickets would be refunded.
He was subsequently treated at a psychiatric centre in LA, according to the lawyer for the tour firm.
At the time, it was reported that West cut short his Sacramento gig on 19 November after playing just three songs and engaging in an extended rant.
In the days before, he had also told an audience he would have voted for Donald Trump, if he had cast a ballot, prompting criticism from some in the hip hop community.
The artist spent "hundreds of thousands of dollars" insuring the tour against cancellation but he is yet to receive any money, the court papers allege.
Lawyer Howard King wrote: "Nor have they provided anything approaching a coherent explanation about why they have not paid, or any indication if they will ever pay or even make a coverage decision, implying that Kanye's use of marijuana may provide them with the basis to deny the claim."
Mr King, who represents West's firm, dismissed any allegation that the use of cannabis resulted in the rapper suffering a "serious, debilitating medical condition".
He described any such contention as "unsupportable".
West spent eight days in a neuropsychiatric centre at UCLA during which it was decided he could not go on with the tour, the court documents say.
Mr King also accuses Lloyd's of providing news outlets with confidential information about West to intimidate him into not taking legal action.
Very Good Touring is claiming alleged breach of contract and wants more than $9,861,000 (£7,464,000) in damages, as well as interest.