The SAG-AFTRA union provides specific protections for actors for nudity and sex scenes. What You Should Know About Nudity Riders:
If your performance in a film will include nudity, partial nudity or simulated sex acts, be sure that you or your representatives have negotiated a nudity rider with production. The nudity rider should include a detailed description of the scene(s), the type of nudity or physical contact required, limitations on use of the footage and production stills (if any), and any other conditions that you and a producer have agreed upon. Remember, even if you have signed a nudity rider, you have the right to withdraw consent at any time prior to filming of the scene. As always, contractual minimums may not be waived by a performer.
The union's Basic Agreement (page 110, PDF page 126) discusses the minimum requirements, including early prior notification, a closed set, and written consent describing what will be shot in the form of a nudity rider. That consent can be withdrawn, and the production has the option to choose to use a double for the actor instead: "If a performer has agreed to appear in such scenes and then withdraws his or her consent, Producer shall have the right to double, but consent may not be withdrawn as to film already photographed."
The blog Film Independent answers some more questions about the rules in Everything You Ever Wanted to Know about Nudity Clauses but Were Too Shy to Ask. Well known actors have the bargaining power to negotiate detailed nudity riders with greater protections, but abuses still happen:
Feldman inserts up to 40 extremely specific provisions in a fully
negotiated "nudity rider" — the addendum to a performer's contract
that spells out the exact requirements
and restrictions of any such scenes — everything from
fluorescent-colored pasties ("It prevents a shot from accidentally
capturing something it shouldn't") to the guarantee of a closed set
("If you have 100 people potentially shooting something with a phone,
iPad, whatever, these things become opportunities for something to
slip out or be hacked, either maliciously or just through
Authentic Talent & Literary Management founder and CEO Jon Rubinstein,
whose company reps Brie Larson and Vera Farmiga, says abuses continue
to be rampant. "Mostly, where you get into trouble is where a producer
or director approaches an actress directly on a set and asks for
something that wasn't negotiated," says Rubinstein.
"It's, 'Look, the whole crew wants to go home. It's midnight. We're
all exhausted. We just have to get this one last shot. The way that we've been doing it isn't working.
Can you drop the towel?' Or, 'That shirt doesn't look right, why don't
you just lose it?' Then suddenly you're standing there and you've got
20 people waiting for you, and you go, 'Ugh, fine.' That happens all
Such a scenario appears to have played out on Lost for star Evangeline Lilly, who recently said she "had a bad experience on set
with being basically cornered into doing a scene partially naked, and
I felt I had no choice in the matter. And I was mortified and I was
trembling when it finished."
Some producers, notably HBO, have recently started hiring intimacy coordinators so that there is a single person responsible for communication, consent, and collaborating with all parties on intimate scenes. You can read an interview with intimacy coordinator Alicia Rodis on how the job works. The union is working with Rodis to develop new polices, so there are likely to be more protections for all union actors in the future.