You should send it in to DC and see if you get some feedback.
Might consider copy writing it first though.
Somehow I didn't notice these responses in this thread until just now.
As I understand it: Once I write down a new story, one that I wrote myself, I automatically own "copyright" on it under modern law. I don't need to put a copy in an envelope and send it to a government office or anything like that. I don't need to write "Copyright by So-and-so on such-and-such a date" anywhere in the text.
On the other hand, about your suggestion to send it to DC . . .
Several months ago I spent some time checking out the online "Submissions Guidelines" of various well-established comic book publishers, particularly as they apply to aspiring writers (since I don't have the training to try to get a gig as an artist on a Batman comic book or whatever).
Here's what it boiled down to.
DC says on their website that they don't want to see any unsolicited art samples or writing samples. The implication is that if you send such material anyway, they'll trash it as soon as they realize what it is.
Image says on their website that they don't want to see any unsolicited writing samples. However, if you already have an art team that's illustrated your script, then you can send them sample pages of your project after those pages have already been pencilled, inked, and lettered. But they make it very clear that if I send them a script they hadn't asked me for, they'll trash it immediately.
Marvel puts it a bit more gently, but it amounts to the same thing. As with DC and Image, if I send them an unsolicited writing sample, they will destroy it. However: I am allowed to send them an inquiry letter talking about my previous experience as a writer. If they are interested, then they may (someday, when they have nothing better to do) send me a reply asking for a writing sample. (I strongly suspect that my chances there would be a lot better if I could say, "I am Lorendiac, writer of twelve produced television scripts, as well as the recent best-selling novel
King Cannibal.")
So basically DC, Marvel, and Image are all saying: "If we never heard of you before, and you just want to break into the field as a writer, go pester somebody else! We're not really interested!"
Dark Horse, on the other hand, says it will actually look at unsolicited writing samples; scripts for new projects, that sort of thing. If I ever break in, that will probably be the place.