A big law firm’s novel lawsuit filed on behalf of a woman who says she was a victim of revenge pornography may be complicated by a decision in a related criminal case.

Federal prosecutors in Los Angeles decided last month to drop a two-year-old criminal case against the woman’s former boyfriend accusing him of posting sexually explicit images of her online.

The prosecutors asked a federal judge to dismiss the indictment charging David K. Elam II with stalking, aggravated identity theft and unauthorized access to the computer of the woman, whom he had met through an online dating service. On March 21, Judge Manuel L. Real of Federal District Court for the Central District of California granted the order and dismissed the case against Mr. Elam.

The end of the criminal case against Mr. Elam, 30, could pose a quandary for lawyers from the law firm K&L Gates’s Cyber Civil Rights Legal Project, which has been providing legal representation to the woman and others who are say they are victims of “revenge porn” — a type of online harassment that occurs when former lovers or hackers post sexually explicit images of people online without their permission.