The Passenger Services Act has been around almost forever. It has required foreign flagged vessels to stop at a "distant" foreign port when traveling departing from US port , and before returning/or going to another US port.
The proposal now is to ammend it to require a 48 hr. stay at a foreign port. NCL originally asked for the change because they are the only US flagged cruise line, meaning they employ largely US citizens, and abide by US labor laws, sailing Hawaii.
The problem is now the commitee examining the issue has recommended the change, but it would cover ALL ships sailing to/from the U.S.... including the Caribbean.
This would have a drastic affect on the cruise industry as a whole, requiring a huge change in itineraries. For example, sailing from Miami, ships wouldn't have time in to get to some more southerly islands. They'd have to adapt their itineraries for the 48 hr port visit requirement.
With the rising costs of fuel I can imagine many cruise lines almost being forced to spend the required 48 hrs in Nassau. If it happens, it's going to be a mess!