Here’s the situation. Currently in American movies, screenwriters are listed in the opening credits, with the wording “Written by,” “Screenplay by.” or “Story by.” (Check here for what these terms mean.) These screen credits are meant to denote the “author” of the script. In cases where there are multiple writers, arbitration is often involved to determine who should receive what credit — if any.
Under the current system, a writer who’s spent several months working on a given film may find her name is nowhere on the final product. Is that reasonable, considering the guy who drove the catering truck is listed? (Before you send angry emails: yes, catering’s important, and so are drivers. But they don’t shape the movie you see on screen.)
For years, there’s been discussion about including a list of contributing writers in the end scroll — writers who may not have done enough work to receive real writing credit, but nevertheless contributed. Personally, I like the idea, but I certainly understand other writers’ objections. Does it diminish the perceived authorship of the front-credit writer(s)? Possibly. On the whole, is it worth it? In my opinion, yes.
You can find a range of other opinions here.