The owner and manager of the massive container ship that took down the Francis Scott Key Bridge last month should be held fully liable for the deadly collapse, according to court papers filed Monday on behalf of Baltimore's mayor and city council.The two companies filed a petition soon after the March 26 collapse asking a court to cap their liability under a pre-Civil War provision of an 1851 maritime law — a routine but important procedure for such cases. A federal court in Maryland will ultimately decide who's responsible and how much they owe in what could become one of the most expensive maritime disasters in history.Singapore-based Grace Ocean Private Ltd. owns the Dali, the vessel that veered off course and slammed into the bridge. Synergy Marine Pte Ltd., also based in Singapore, is the ship's manager.In their filing Monday, attorneys for the city accused them of negligence, arguing the companies should have realized the Dali was unfit for its voyage and manned the ship with a competent crew, among other issues. A spokesperson for the companies said Monday that it would be inappropriate to comment on the pending litigation.The ship was headed to Sri Lanka when it lost power shortly after leaving Baltimore and struck one of the bridge's support columns, collapsing the span and sending six members of a roadwork crew plunging to their deaths."For more than four decades, cargo ships made thousands of trips every year under the Key Bridge without incident," the city's complaint reads. "There was nothing about March 26, 2024 that should have changed that."FBI agents boarded the stalled ship last week amid a criminal investigation. A separate federal probe by the National Transportation Safety Board will include an inquiry into whether the ship experienced power issues before starting its voyage, officials have said. That investigation will focus generally on the Dali's electrical system.In their earlier petition, Grace Ocean and Synergy sought to cap their liability at roughly $43.6 million. The petition estimates that the vessel itself is valued at up to $90 million and was owed over $1.1 million in income from freight. The estimate also deducts two major expenses: at least $28 million in repair costs and at least $19.5 million in salvage costs.Grace Ocean also recently initiated a process requiring owners of the cargo on board to cover some of the salvage costs. The company made a "general average" declaration, which allows a third-party adjuster to determine what each stakeholder should contribute.Baltimore leaders argue the ship's owner and manager should be held responsible for their role in the disaster, which has halted most maritime traffic through the Port of Baltimore and disrupted an important east coast trucking route. The economic impacts could be devastating for the Baltimore region, the filing says. "Petitioners' negligence caused them to destroy the Key Bridge, and singlehandedly shut down the Port of Baltimore, a source of jobs, municipal revenue, and no small amount of pride for the City of Baltimore and its residents," the attorneys wrote.Lawyers representing victims of the collapse and their families also have pledged to hold the companies accountable and oppose their request for limited liability.In the meantime, salvage crews are working to remove thousands of tons of collapsed steel and concrete from the Patapsco River. They've opened three temporary channels to allow some vessels to pass through the area, but the port's main shipping channel is expected to remain closed for several more weeks.