that is why
"In all my years of scam-tracking, I know of just one--count 'em, one--documented incidence of piracy by a disreputable literary agency."
Since theft is extremely rare, this is why writers should just focus on submitting and selling work. Should an unscrupolous person use your work without permission after you've sold it, the publisher, producer, or studio will deal with them in a court of law.
Also, an agency that is known as disreputable will be shunned by the industry.
I think what happens more commonly is that people do write manuscripts and screenplays that have similiar concepts. And if one is purchase, sometimes people in the past have wanted to sue.
As Victoria said, it's when your work becomes known that you really have to worry. Look at this link.
www.eonline.com/News/Item...%2C00.html
Mattel had sued Aqua over the sexually suggestive song Barbie Girl. The song is about the plastic dolls Ken and Barbie.
I also remember reading about, a Bollywood film director who read an English novelist's book. He blatantly used the same names for the characters and everything. When she found out, she went to India and sued. His tv series was taken off the air temporarily, while they worked on her demands to be paid and to be credited.