Updated

How much or how little skin an actor agrees to show in a movie is usually spelled out beforehand in a detailed nudity rider.

Actress Anne Green is being sued by the production company True Crime because they said she balked at nude scenes to which she had agreed in her nudity rider, causing cost overruns. (She initially sued them for creating a hostile work environment.)

But Green's case is exceptional, as the contracts actors sign when they agree to a role that involves nudity and sexual situations are carefully parsed and vetted scene by scene, image by image. Indeed a nudity rider typically includes which body parts can be shown, from which angle and for how long.

“These documents are typically signed well in advance of production in an effort to avoid and problems down the road during production,” explained Alec Shankman, an agent at leading Hollywood firm Abrahams.

The SAG-AFTRA union mandates that “The Producer’s representative will notify the performer (or his representative) of any nudity or sex acts expected in the role (if known by management at the time) prior to the first interview or audition... The performer shall have prior notification of any interview or audition requiring nudity and shall have absolute right to have a person of the performer’s choice present at the audition.”

More On This...

Experts tell FOX411 the nudity rider ensures the actor/actress knows exactly what is expected of them, helps prevent exploitation, and can also make or break a career. Typically, the actor and his/her representation negotiate the terms of a nudity rider for maximum control over variables like how a scene is shot, the use of body doubles, and what kind of coverage -- pasties, body suits, etc. -- the actor can demand.

The sample nudity Rider supplied by FTM (Film, Television & Media Arts) specified that “such services shall require Player to appear nude and/or semi-nude, and/or perform simulated sex act (s), as the case may be, in the Picture,” and goes on to state the “general description” of what would be required with regards to “the extent of such nudity, and the type of physical contact required in such designated simulated sex acts.” This can include descriptions like “I will show side boob for three seconds in a moving shot,” or “I will show the left cheek from the left side dim light.”

And while actors want as much control as possible, experts say some lesser known actors can use a liberal nudity rider to advance their careers.

“Some actors/actresses believe that their avenue to stardom is to show nudity in movies. For example, Sharon Stone’s successful career was based on her showing nudity in ‘Basic Instinct,’” said attorney Leo Terrell of CleartheCourt.com. “The same with Kim Basinger in ‘9 1/2 Weeks.’ These actresses were unknown, but were really discovered and became famous, so to speak, due to doing a nude scene for a movie.”

Once you are famous, the power dynamic shifts.

“Successful actors and actresses who call for major salaries have total control over whether nudity is even shown in their movies," said Terrell. "On the other hand, the relatively unknown actors/actresses have little control over the nudity rider.”

Follow @holliesmckay on Twitter.