I would bet heavily on those being produced illegitimately. I would also wager that they are very low quality -- they look like full-color photos on black shirts, so the only option there would be the crappy opaque transfers.
For them to be legal, you will need to contact the famous rappers lawyers, or their estate(if their dead) and ask them if you can sell shirts with the persons picture on them. They will probably charge you a large up front cost, and then a percentage of each sale. Most people just do it without permission.
However if it is your photo that you've used (meaning you took the picture) than you have a leg to stand on.
It's not so much the artist that can sue you, but the photographer. Much the same way you can take a picture of President Bush and put it on a T-shirt; the USA cannot sue you for that.
I don't want to be too harsh, but there's enough misinformation out there without people offering advice they're not sure of. Granted I do it myself sometimes, but when in doubt it's best to err on the side of caution. Although you did say "have a leg to stand on" rather than "can use", so you're about right I guess. It's one shakey arthritic leg though, so I'd want Johnny Cochran as a crutch if I was going to try it.
There's a reason we have model release forms, and that reason is that people's image can't (generally) be used without consent. Since this isn't a copyright issue so much as a privacy and/or compensation issue, that becomes especially true in a commercial context.
There is a list of ever-growing exceptions thanks to the pioneering work of the paparazzi (oh don't you just love those invaders of personal freedom? need to use a public restroom, Mr. Gibson? hope you don't mind photos of your wang on the front page!), but it's a pretty complicated issue.
Even having taken a picture yourself won't necessarily protect you, because you have no legal rights to publish that picture. I doubt you could even get away with what the trash mags do - they're (ostensibly) reporting on the news.
The fact is though that none of this stuff is particularly cut and dried, which is why there is so much misinformation out there. Part of the problem is that what you can (legally) get away with isn't necessarily written into law. Someone sues, a precedent is established for another exception, and so it goes. But I don't think "it's okay to print pictures of girls topless in trashy magazines without their permission if they've ever been in print or on a screen with permission" was written into the original law (even then though, trash magazines are successfully sued from time to time - so it really isn't entirely clear where the boundaries lie).
Using the face of any artist without permition to re-sell and profit is rape.
Legal or Not.
Having the pleasure to work with some Hip-Hop artists, dances, crews etc. I can tell you that they do not have a problem with you making a shirt at home for yourself.
The peeps who do have a problem with rip-off's are the peeps who pay big bucks for the rights to sell these shirts at concerts etc.
Is that fair or what ?
Look at ebay and how may cheap photo transfers are beeing sold that are rip-offs.
Using the face of any artist without permition to re-sell and profit is rape.
Legal or Not.
Foxy, rape is a very separate thing alltogether. I do agree that they are scum. Some people think that just because something is legal, then it is right.
One thing that gets to me so much is ethics. I would rather make a modest living knowing that I did things the "right" way, than being filthy rich and stepping on other people. But then we get into morals and ethics and what is
"right" and what is "wrong", which is something for another time and place. But I would love for all of these famous people that "companies" are leeching off of to spend some of their money to find out who is stealing from them and sue the hell out of 'em.
Politicians are seperate...you an use them on t-shirts. That is the one exception.
This is not 100% true either... a person has to have been elected and held a political office. Politicians seeking office do not count under this exception. I know it's minute but I thought I'd point it out.
Hip Hop Picture shirts 
