“They spend a year or two working on material that is the basis of their income, and then it ends up in an unfinished form online for free,” said Noam Dworman, owner of the Comedy Cellar in New York and a friend of Louis C.K.’s. “It’s terrible for them.”

Over the past several years, cellphone bans, intended to curb such leaks, have become standard practice, governing performances by brand-name acts like Chris Rock, Ali Wong, Kevin Hart and Hannah Gadsby. Louis C.K., a longtime proponent of the bans who has been the target of leaks in the past, also imposed one at the Minneapolis gigs.

But by seeking to prohibit not only recording but all reproduction of his jokes, “in whole or in part,” in any medium, he is pushing the demand for discretion to a new extreme. And he risks further antagonizing audiences amid a tumultuous comeback — following an admission of sexual misconduct in 2017 and a nine-month hiatus — that has drawn widespread criticism, both for its timing and its taste level. After a leaked set last December, he drew a backlash for mocking survivors of the Stoneman Douglas High School shooting.

And then there is the technical question: Is such a ban even legal?

“It’s overreaching in terms of copyright law,” said Jeanne Fromer, a law professor and co-director of the Engelberg Center on Innovation Law and Policy at New York University. “The law grants certain rights, but it withholds certain others.”

Fromer noted that the language in the ban declares Louis C.K. the owner of all “jokes and sketches” in his set, but the question of whether one can copyright a joke is controversial and depends on secondary questions of the joke’s originality, length and whether it is essentially an idea, which is not protected by copyright.