"legally determined" is correct and can be used in written English.
You can use it when you want to indicate that a decision or judgment has been made according to the law. For example, "The court legally determined that the defendant was not guilty of the charges."
It had never been legally determined who was a U.S. citizen.
When an invention arises from collaborative work with an institution or company, the IP may be jointly owned if at least one employee of each institution is legally determined to be an inventor.
It is unclear whether Mr. Alexis's psychiatric issues ever progressed to the point that he was involuntarily committed to a mental health institution, or legally determined to be mentally ill or incompetent, either of which would have barred him from buying a gun.
Today the Administration went the final step, announcing that EPA has legally determined greenhouse gasses to be a danger to human health under the Clean Air Act.
The European Union called this morning for "a return to calm," and urged the Congolese government to "respect the legally determined electoral timetable".
The Klamath water rights were finalized barely a month ago and this process once-and-for all legally determined who gets what water in dry years.
Costi acknowledged Shaw's proposal would allow that gap in the refugee convention to be filled but said the problem would be legally determining whether an environmental migrant was still able to live in their home country.
"Local authorities are responsible for assessing and legally determining contaminated land within their communities, and we are supporting Kensington & Chelsea council to come to a decision on what actions are most appropriate.
The Iowa caucus, despite its position at the center of the political universe every four years, is nothing more than a nonbinding preference poll that does not legally determine who gets the state's 25 delegates to the Republican nominating convention.
It's difficult to keep track of them, and it's difficult to legally determine who their employer is.
Because the lab notebooks and raw data files dealing with the experiments have disappeared, it has not been possible to legally determine who is at fault, according to the university.
