Paramount conceded that its fight with 12 state AGs will not end in a quick knockout, but will drag on for months.

The biggest merger in modern Hollywood history once looked like a done deal. It’s suddenly facing a serious legal challenge from a group of state attorneys general.

A group of 12 state attorneys general allege the Paramount-Warner Bros. merger would violate antitrust laws and are seeking a preliminary injunction to halt the deal. Here's a…