Paris Hilton will not have to pay $8.3m in damages for failing to promote the 2006 turkey Pledge This! a court found yesterday. But she may yet have to return a proportion of her $1m acting fee, US district judge Federico Moreno said in Miami.

The hotel heiress and socialite was being sued by receivers for Worldwide Entertainment Group, a now defunct entertainment firm that was the major investor in the National Lampoon film. The lawsuit claimed she violated her contract by rejecting or ignoring requests by producers to appear on talkshows or undertake radio and magazine interviews to promote the movie.

In his ruling, Moreno said the evidence suggested that Pledge This! lost money "because the film's inexperienced producers hastily cobbled together a wholly inadequate marketing plan", rather than because Hilton had failed to meet her commitments. But he gave prosecutors until 26 August to submit arguments that she should pay back parts of her acting and producing fee.

Hilton played the president of a sorority at fictional South Beach university in Pledge This!, which made just $2.9m (£1.8m). She testified during a two-day trial last month that she had done her best to promote the movie.

"If I have my name attached to something, I want it to be as big as it can be," she said, insisting she spent more than two years promoting the film, including two high-profile trips to the Cannes film festival.

In his ruling, Moreno also said he was finding against the Pledge This! producers because the film was "hardly destined for critical acclaim". The film currently sits at No 27 on the Internet Movie Database's user-voted list of the worst movies of all time.