Cruise ship inspections vary by ship and country

In addition to the regulations of the International Maritime Organization, a United Nations agency, a ship is subject to the laws of the country whose flag it flies. The ship may also be subject to the laws of a country where it stops.

The Carnival Triumph sails under a Bahamian flag, so authorities there are taking the lead in investigating the incident. But because the Triumph stops in U.S. ports and carries U.S. passengers, the U.S. Coast Guard has some inspection oversight over the vessel. The Coast Guard issued a certificate of compliance for the Carnival Triumph on May 17, 2012 after the ship's annual inspection.

The Coast Guard and the National Transportation Safety Board have also launched an investigation into the cause of the engine room fire.

In contrast, the Costa Concordia, which ran aground and sank off the coast of Italy in January 2012, didn't stop in U.S. ports carrying U.S. passengers, so it wasn't subject to U.S. Coast Guard regulation.

Passengers may have a legal case

Carnival's ticket contract says the cruise line is not "liable to the passenger for damages for emotional distress, mental suffering/anguish or psychological injury of any kind under any circumstances, except when such damages were caused by the negligence of Carnival and resulted from the same passenger sustaining actual physical injury, or having been at risk of actual physical injury."

While no physical injuries have been reported, if a passenger contracted a significant disease, such as hepatitis, from unsanitary conditions on the ship, maritime trial attorney John H. (Jack) Hickey believes physical injury could be argued.

"I think that a case can be made that everyone on that ship is at risk of actual physical injury," he said.

Will passengers file suit and can they win? Yes and yes, Hickey said.

Carnival's contract prohibits a class action suit, but Hickey said he's not sure whether it is legally enforceable.

Hickey has never filed suit over a cruise ship stranding, but he said these circumstances, particularly the reports of sewage on decks, are exceptional.

"It's a public health disaster in the making."