I can tell you right now that it would not be likely to make a difference. Read some research on risk-taking among gay men, from any of the various cohorts being studied around just North America or Europe. Sexual risk behaviour isn’t deterred by punitive threats, but by power and will. You have to give them a reason to believe in the need to be safe, and quite frankly, from the research I’ve read from the VIDUS and Omega cohorts in Vancouver and Montreal, the Ontario Men’s Survey, and the cohorts in San Francisco and New York who’s names I can’t remember (plus a whole bunch of other studies from all over the world), gay men engage in risk behaviours because they genuinely aren’t worried about getting sick. Many of them feel that even if they do contract HIV, they will still be fine because of HAART. Further, many cite safe-sex fatigue as a reason, meaning that they are simply tired of having to be careful (which is a pretty dumb excuse, frankly). And probably the most significant reason is many younger gay men (who were either quite young in the eighties or not even born when AIDS first arose) simply have not had the experience of seeing their friends and lovers die of AIDS. They just don’t see it as something to worry about.
Now, I am on the side of everyone here in saying that knowingly having unprotected sex while positive is reprehensible and should face penalties (in fact, I’m aware of court cases where men have been tried for just that). However, even if this were a good idea fiscally, I don’t think it would work preventatively because of some of the reasons listed (denying contact, claiming it was someone else that infected them, etc). HIV can be traced by strain, but the vast majority of HIV case in North America are HIV-1 subtype B, so unless they show a new strain or some sort of mutation it might be tough to pinpoint who exactly passed the disease to whom. The best way to do it is examine social networks and look for patterns. Further, the men who engage in barebacking consistently show a lack of concern for the risks, and I just don’t think this would change their outlook, since there’s only so much money you can take from them.
Prevention only really works when you get people to buy into your message. That takes something significant, like a charismatic leader, or, sadly, a series of negative events, like the death of a large number of HIV-positive people, before others will start to listen.
Incidently, two more points: the story of Gaetan Dugas is no where near definite, and is one possible scenario explaining the spread of HIV (though probably only a very small part of it is true). And also, for partner notification, the main reason generally used for not informing partners stems from the social stigma traditionally attached to HIV and AIDS, wherein letting anyone know you have it leads to discrimination and so on. So the fear was always that if one knows that people will find out that one is positive (once discovered by testing), one will be less likely to come forward for testing in the first place, and since HIV can remain so quiet and unnoticed in the body for a long time, it behooves public health officials to do what they can to get people tested. I disagree, because I believe the rights of the potential victim (for lack of a better word) outweigh the rights of the tester, so long as there is a definitive guarantee of privacy otherwise (officials can inform partners, but no one else).