The lawyers call them a "a flagrant violation of copyright laws".
Other celebrities who had photos stolen during the latest hack include Tiger Woods, Lindsey Vonn, Miley Cyrus, and Katharine McPhee. The Daily Mail reports some have also called in lawyers to have the photos removed.
Rumours about a romance between Maxwell, a Victoria's Secret model, and Stewart, the star of the Twilight film series, began swirling late last year but seemed to be confirmed in January when they were spotted kissing.