I feel I have to interject here, because there seems to be some confusion with regards to how STIs function and the value of protection in that regard - and its rather worrisome.
Condoms are certainly going to help protect against transfer of some diseases, however, diseases are transferred in bodily fluids - and wearing a condom doesn't magically stop body fluid transfer.
Condoms are 99% effective in blocking pregnancy, not fluid transfer - its a physical barrier to keep male ejaculate (containing sperm) from getting into the female reproductive tract.
And given that fact, it does have SOME value in terms of blocking disease transfer... but nowhere near the 99% of pregnancy blockage.
There are diseases that can penetrate the condom, for one thing, meaning they offer little-to-no protection in that regard. And, as mentioned, condoms sometimes break, posing another hazard.
But there's another aspect of this I feel some folks are totally missing...
Now, I don't know what kind of sex you folks are having, but in my experience, even with a condom, body fluid contamination of various bits of your body is generally going to happen - a lot.
Unless you're having, like, the lamest sex ever, this stuff - particularly in the case of female fluids - is going to be getting all over the place on your partner: on their face, on their non-condom'd crotch, on their hands. And on plenty of other places/things depending on exactly how freaky your deaky may be... aky.
And most diseases don't immediately die upon exiting your body - they can survive awhile, especially if sheathed in a layer of protective bodily fluids. Things that come in contact with that fluid then become a vector for transfer of the disease.
Say, for example, you condom up and have sex, and chances are (again, unless you're really lame) your fingers make the trip to Vajajay-ville. Then you go to take the condom off.
*ANNOYING BUZZER SOUND* You may have just been infected, your fingers having become a vector for transfer during your bedroom romp. Likewise if, say, your partner goes down on you or you go down on them - something not terribly common with a condom on - then the two of you make out a bit, and make another trip down south.
I could go on with these theoretical scenarios, but I'm sure you get the idea.
To put it rather bluntly, there is no such thing as 'safe sex' when it comes to STI transfer, unless you're talking about knowing someone well and trusting them fully beforehand... or using some kind of crazy full-body condom.
Or, as previously mentioned, having the lamest, most robotic sex imaginable.
Remember kids - its the fluids that contain the nasty bad stuff, and if you get that fluid on something, that something then has the potential to pass whatever is in the fluid to other areas that something touches.
Now you know - AND KNOWING IS HALF THE BATTLE!
Oh, and uh, I'd be okay with the STI card/branding thing, I guess, to some degree. It seems like a difficult issue to 'police' effectively, as many people with STIs dont realize they're infected, but its a move towards a requirement for transparency with regards to this issue that I feel would be better for our society on the whole.