Alec Baldwin is looking to have one of the charges of involuntary manslaughter, which could see him jailed for five years, thrown out by a US court.
The actor's lawyers have accused New Mexico prosecutors of committing an "elementary legal error" after charging him under a statute which didn't exist at the time of the fatal Rust shooting.
Baldwin has been charged with two counts of involuntary manslaughter by the Santa Fe District Attorney’s office, over the death of cinematographer Halyna Hutchins.
The mother-of-one was killed on the set of Rust in October 2021 when Baldwin discharged a prop gun, which also injured the film's director Joel Souza.
Halyna, 42, was airlifted to hospital from the New Mexico set but died of her injuries.
The first of Baldwin's charges can be referred to as involuntary manslaughter and requires proof of underlying negligence.
The second charge is involuntary manslaughter in the commission of a lawful act, which requires proof that there was more than simple negligence involved in a death.
It includes a firearm enhancement, which makes the crime punishable by a mandatory five years in jail.
But in a filing on Friday, Baldwin's lawyers said such enhancement had only been enacted last May, seven months after the fatal incident.
They added that the charge was "unlawful".
"The prosecutors, in this case, have committed an unconstitutional and elementary legal error by charging Mr Baldwin under a statute that did not exist on the date of the accident," the motion read.
"It thus appears that the government intended to charge the current version of the firearm enhancement statute, which was not enacted until May 18, 2022, seven months after the accident."
The filing added: "Mr Baldwin also respectfully requests that the Court decline to bind over that enhancement."
Baldwin is due to make his first appearance in US court in two weeks on February 24, to face the criminal charges.
It comes after a separate civil lawsuit was filed on Thursday by the family of Ms Hutchins.
The family are suing Baldwin and the Rust movie production company for alleged battery, intentional infliction of emotional distress, negligence, and loss of consortium.
Loss of consortium is a claim which seeks to recover compensation for damage to certain relationships that are mutually dependent.
