But how long can the entertainment business go on as normal in an environment where those who come up with the ideas are not on speaking terms with those who have traditionally helped bring their work to the screen?

A few writers have expressed frustration with union leaders, questioning the hard-line approach. At the other end of the labor fight, one relatively small talent agency, Verve, agreed to the terms the writers have demanded.

For the most part, however, both sides have held firm.

In their April lawsuit, the writers called packaging a gross conflict of interest and illegal. Separately, they have also criticized the agencies’ recent entry into the content business, with the creation of affiliated studios of their own — another conflict of interest, in the writers’ view. To bolster their argument, they said their wages had declined, despite the fact that there were more television shows than ever, now that Netflix, Amazon and Apple have come to town, hungry for content.

In the lawsuit filed on Monday, William Morris Endeavor hit back.

“The reality is that agency packaging and content affiliates provide significant benefits to writers who (used to be able to) exercise their freedom of choice to take advantage such of practices,” the complaint said. “In the words of W.G.A.’s leadership, the boycott to enforce their unlawful bans is nothing more than a ‘power grab’ masquerading as a legitimate exercise of union authority.”

The Writers Guild of America West responded by saying in a statement, “There is no merit to WME’s lawsuit, and the guild will not be bullied into a bad deal.”

Winston & Strawn — an international law firm that has represented the National Basketball Association players union in disputes with the league — is working on behalf of William Morris Endeavor.

Creative Artists Agency responded to the guild’s lawsuit earlier this month by saying that the union did not have standing to sue in the first place. The other two major talent agencies — United Talent Agency and ICM Partners — are expected to file their responses in the coming days.