Hawaii's mandatory quarantine of travellers to contain the spread of Covid-19, is discriminatory, the United States Justice Department says.
The department filed a Statement of Interest this week in a legal challenge to the 14-day quarantine instigated by Governor David Ige.
It said the emergency rule was unfair to non-residents and probably violated constitutional protections of inter-state travel.
The US Attorney for Hawaii, Kenji Price, said there were bounds on the discretion of public officials during a crisis.
But the state said the department's conclusions had no merit.