Sovereign immunity ("The king can do no wrong") is a medieval legal doctrine that holds that a sovereign cannot be sued without its consent. By signing the interstate compact that created the Washington Metropolitan Area Transit Authority, the courts have ruled, Virginia, Maryland and the District of Columbia transferred their own sovereign immunity to WMATA. So in most cases, Metro can't be sued for negligence even when it's clearly at fault.

There are exceptions. In January, Metro agreed to pay $1.6 million to settle just 84 claims from the 2009 Red Line crash that killed nine people and injured dozens more. Payments to those victims ranged from $333 to $150,000 after the National Transportation Safety Board found Metro at fault for ignoring numerous warnings that its automated track circuits were malfunctioning. Metro has paid millions more to others injured in the accident, but the details of those settlements are under seal. Metro has been operating on herky-jerky manual mode ever since.

Gary Minter boarded a Red Line train at Metro Center on Aug. 19, 2011, his 61st birthday. He was chatting with a fellow teacher when the manually operated train stopped, and then suddenly lurched forward at the Chinatown station, throwing Minter five feet. He landed on an armrest and broke several ribs.

On Feb. 4, Minter filed a modest $5,000 claim against Metro to cover medical expenses related to the fall. On April 30, Superior Court Judge Elizabeth Wingo denied his request.

Wingo's ruling was consistent with a January 2012 decision by the Maryland Court of Special Appeals, which overturned a jury award to Veronica Tinsley, who slipped and broke her ankle on a slick Orange Line station platform after Metro employees mopped it during rush hour in violation of the transit agency's own policy. It was also consistent with another ruling that let Metro off the hook for a passenger's fatal heart attack — even though it had failed to properly maintain a defibrillator — on grounds of sovereign immunity.

But allowing Metro to hide behind sovereign immunity to escape the consequences of what would otherwise be considered negligent behavior not only does an injustice to injured passengers, it fosters and encourages the same "anemic safety culture" cited by NTSB as the real underlying cause of the worst accident in Metro's history.

As long as Metro continues to remain unaccountable for its actions, at the very least it should be required to post a warning sign in every station: Ride at your own risk.