When I was a kid there used to be a magazine feature, I think it was in Reader's Digest, called "You Be the Judge." They'd present the essentials of a legal case and then you guessed the outcome before looking to see what really happened. So here's one for you:
A man and a woman are friends and neighbors and both are writers and animal lovers. He's also a producer and actor. She shows him her script about a woman who is obsessed with saving cats. He reads it, likes it, says if she wants him to act in it, he'd be willing. Time goes by. She gets a producer to show her script around, but then she finds out that her friend/neighbor has made a deal with Paramount for a script he wrote about...a woman obsessed with saving dogs. The film (called "Year of the Dog") came out in April and flopped.
She feels betrayed and now they're fighting like...I won't say it. And she's suing him. Interestingly, she's not suing him for copyright infringement. That's probably wise, because it's impossible to protect just an idea, only how an idea is executed. Her case is that because he's a producer, there was an expectation that if he used her idea in any way she would be compensated. (If you want to look into this more via Google, her name is Laura Kightlinger, his is Mike White.)
So: you be the judge--what do you think the outcome will be? My guess is that their relationship and the circumstances in which she showed him the scirpt were ambigous enough (since they were friends, not just writer and producer) that she will not prevail. I also predict it will never get all the way to a trial--the usual outcome of these things is a settlement, which often is less expensive than winning a court case.