– Heather

Actually, this basic question comes up a fair amount, so it’s time I explain a term of art:

SCRIPT DOCTOR
An established screenwriter with significant credits who rewrites a script to address specific concerns, often shortly before production begins.

By this definition, I am a script doctor. I get brought in to help out on big expensive movies — two of which you’ll see in Summer 2008. They pay me significant money to do a few weeks’ work, for which I’ll never get credit. I’m hired for my talent, hopefully, but also my track record in getting movies up on their feet. I enjoy the work, partially because it’s a chance to date other movies while being married to the ones I’m “really” writing.

The thing is, no one who actually is a script doctor uses the term. My hunch is that some journalist made it up, likely because the work the screenwriter is doing on a script in this stage is often described as “surgical” — you’re going in to fix a very specific issue, and leaving everything else intact. Steve Zaillian is often brought up as script doctor, but make no mistake, that’s not a side-job to his writing career. It is part of his writing career.

To summarize, Heather, a script doctor is a screenwriter. So if that’s your friend’s goal, he needs to write a lot of scripts and have them produced. There are also non-writers involved in the process of shaping a story — producers, development executives — but their focus is working with a writer. If that’s his ambition, he’ll start out in the trenches, answering phones and writing script coverage.

UPDATE:
Damn, I knew I’d answered this before. In fact, it’s the fifth hit on Google for “script doctor.” Here’s what I said in 2004:

In the industry, a script doctor is an established screenwriter with a bunch of credits who comes in on a project shortly before production and does a rewrite to fix some specific, nagging problems. (Or, depending on your perspective, destroys the things that made the project unique.) Steve Zaillian is a highly-regarded script doctor. Arguably, I could be considered a script doctor, because I’ve done a fair number of these 23rd-hour emergency jobs. But no one’s business card reads “script doctor.” It’s a specific task within screenwriting, but not really a profession in-and-of itself.

A lot of times, the work you do on these projects is described as “surgical,” which fits well with the script doctor moniker. Generally, you’re not rewriting the whole script. You’re fixing a few key sections that aren’t working.

It’s strange to read an answer written nearly three years ago and see the same phrasing, same examples. I guess it’s good that I’m consistent.

By the way, I’ve added this to the wiki, in anticipation of the next time someone asks the question.