Ron Nyswaner, the Oscar-nominated screenwriter of Philadelphia, has hinted that his recent lesbian-themed drama, Freeheld, was “degayed” by producers against his wishes.

Speaking at the Los Angeles LGBT Center’s Vanguard awards, Nyswaner vowed never again to hand over creative control on his movies after revealing that key characters in one of his recent projects were “turned into lesbians with a lower case ‘l’”.

“We must be careful – as we become mainstream – that we don’t forget we’re the descendants of outlaws and rebels. We must resist the tendency to be degayed,” he said. “One of my recent gay-themed projects had a lot of potential. But the producers became fearful. The gay characters were idealised. Their edges were smoothed out. The conflict between them was softened. Over my vigorous objections by the way, for the record.

“The main characters were turned into lesbians with a lower case ‘l’. Because God forbid someone might think we were making a movie about a couple of dykes. Out of fear, they were normalised. We must remember – and insist that others honour – our history and our very specific gay culture. We are the inheritors of a culture that was created from pain and invisibility. From being different.”

Nyswaner continued: “Tonight, I make this pledge to you. I’m done with fear. I will never work on something in which I don’t have some measure of artistic authority. I will create art in which gay characters are not normalised. Art that features LBGT characters who are fearless, powerful and scary motherfuckers.”

While the screenwriter did not mention Freeheld by name, it is clear that he was referring to the Peter Solett-directed drama, which debuted at the Toronto film festival in September but has received middling critical notices. The film stars Julianne Moore as critically ill New Jersey detective Laurel Hester, who finds obstacles in her path after trying to leave her pension benefits to domestic partner Stacie Andree, played by Ellen Page.

Freeheld was heavily promoted by Page, who came out as gay last year and had been attached to the film for six years before production began. However, the drama, which was once tipped to be part of the 2016 Oscars conversation, now finds itself at risk of a similar fate to the much-maligned recent civil rights drama Stonewall, as an example of a gay-themed movie which had its spiky edges removed to appease mainstream audiences.

Like Stonewall, which covered protests against police harassment of homosexuals who frequented the Stonewall Inn in Greenwich Village, New York in 1969, Freeheld was based on a true story. The real-life Laurel Hester died in 2006 after successfully convincing Republican authorities in Ocean County, New Jersey to extend pension benefits to registered domestic partners seven years before the state enshrined gay marriage in law. Her story was also told in an Oscar-winning short film, also titled Freeheld, in 2007.