Sure I have time...Some of these suggestions the Cruise lines might do in the future and some might be a little harder..
(1) The US government could make recipical agreements with Ships flagged in different country's to enforce US law for cruise ships leaving and returning to US ports. same with Canada, Britian and other "Host" Country's to enforce their National laws..
(2) In the US,..Establish a Federal Law enforcement program similar to the Air Marshal program with a Federal agent trained in Investigations and prevention to be placed on every ship with the cost being paid in part by the Cruise line and the passengers..sailing out of the US.
(3) The US could lower taxes on "Flagging" cruise ships that primary sail out to the US to make this process more easier.
(4) On ships that sail short cruises or that are known "Party boats" hire competent Security Officers
perferbly former LEO or Military..Give these officer the proper tools and training...None of this Scene where officers from Carnival were kicking the Aussie's on the ground..
As I, stated above, Hire and Pay these officers properly...Lots of MP's and Marines leave the service every day, here in US, Canada, Britian...Especially when you looking at Head of Security for your ship
Hire a Gunny Sgt from the US or a Royal Marine...not some guy from Indonesia...