How often, and badly, do screenplays get changed, or butchered, by a studio after they get their hands on it? I mean, after you've slaved and sweated over a screenplay and got lucky enough to sell it, when does the producer get in there and say, "Okay, let's change this," and the artsy director gets in there and says, "This is MY vision of your story," and some other writers get in there and booger up everything you wrote, until what shows up on screen is nothing like you wrote. Suddenly, what could have been a good, or even great motion picture, becomes another piece of formulaic trash, with your name attached to it in the credits! Even though most of what was spoken on that screen was never put down on paper by you. And how do you avoid this from happening to yor work? Some years ago, I read the screenplay for Twister. I also saw the movie, and it was very different from the screenplay in many ways. Yes, there were some sceens that were the same, but it was drastically changed. Some things were good changes, but overall, the original screenplay seemed far superior to the final film.
That a screenplay is rewritten?
Virtually always.
That it's 'badly rewritten' -- that also can happen frequently. While most contracts call for a rewrite and a polish, for every contractually mandated rewrite, there are generally, two, three, four, or half a dozen drafts that are "off the books" -- drafts that writers do that aren't contracted for and for which they don't get paid.
This is one of those open secrets that pretty much everybody in the industry knows about, the guild knows about it -- but the brutal fact is, if a writer refuses to do these free drafts, then he's a considered to be a "difficult" writer and he doesn't get hired.
Beyond that, it's quite common -- far common than not, for scripts to have multiple writers, even if they are not ultimately credited. The process by which writers receive credit -- which writers and how many writers, is one that is controlled by the guild and one of the guild rules states that no matter how many writers work on a project -- and there can be five, ten, or any number of writers, only three writers (or writing teams) can receive on screen credit.
A fairly byzantine process of evaluating who contributed what percentage of the material to the final draft of the screenplay (as opposed to the final version of the movie) is what determines who gets that final credit.
As to what can be done? Unless you are the also the director or the producer or have a close personal relationship with one or the other, (and sometimes even that won't help) there really isn't anything you can do about it.
It's not your money making the movie and once you sell the script, it's no longer your script. You no longer have any rights to it. It belongs to them and they can do whatever they want to it. In fact, if they pay you above a certain amount, you don't even have the right (under guild rules) to take your name off of it.
Now, you may ask why the Director has the right to take his name off of a project but not the writer.
The same way that the director's royalties are enormously larger that the writer's royalties on a movie.
That's because the DGA is a much more powerful union the WGA.
Because directors are much more powerful that writers.
NMS
