Lorries could be seized and drivers arrested after a judge ruled a protest blocking one of the main routes between the US and Canada must now end.
Traffic across the Ambassador Bridge has been halted all week as truckers demonstrate against a Covid vaccine mandate.
Canadian Prime Minister Justin Trudeau says the consequences for those staying put are getting more severe:
"The boarder cannot and will not remain closed. I can assure you that the RCMP is working with provincial and local police departments to enforce the law."
