In my Scientific American column this month I asked a question that thousands of people have probably asked before: In those aggressive terms of service agreements that bind participation in Facebook, Instagram, Gmail, YouTube and other free services, what am I actually agreeing to? How far can they go in using stuff that I post? What can they do with my stuff?

It sure sounds like the answer is, “anything they feel like.” I mean, come on. Here’s what Facebook tried to get away with in 2009 (a public backlash forced it to tone down the language): “You hereby grant Facebook an irrevocable, perpetual, nonexclusive, transferable, fully paid, worldwide license (with the right to sublicense) to (a) use, copy, publish, stream, store, retain, publicly perform or display, transmit, scan, reformat, modify, edit, frame, translate, excerpt, adapt, create derivative works and distribute (through multiple tiers), any User Content you (i) Post on or in connection with the Facebook Service or the promotion thereof.”

“Modify?” “Edit?” “Adapt?” Does that mean that Facebook could take a short film I’ve posted, reedit it, and do whatever it wishes?

My legal consultant for that column, Alan Friel, pointed out two reasons why you don’t have to worry about that sort of thing.

First, the law is on your side—a law you might not expect. It’s the DMCA (Digital Millennium Copyright Act), which most of us think of as the “software piracy” law. If a site started making derivative works of your material, even using your photos in ads, or allowing third parties to do so without your permission, they would be violating the DMCA. By agreeing with the companies' terms of service, you might be saying "it's okay with me" for the sites to do what they please with your material. But the companies, in turn, would probably rather abide by the law than risk getting sued just to use your party pic in an ad. 

Furthermore, it would be nearly impossible for the service to make sure that your material had all the necessary rights for it to publish your stuff on its own. In other words, they would have to do a lot of digging to make sure you owned the copyright, licensing rights, etcetera.  “So practically,” Friel says, “a publisher would be at too great a risk of third-party claims to ever do more than merely distribute the user-generated content.” (The clauses in question are simply meant to give the service the right to display your material on its site—to tag it, make it searchable, adapt its format and so on.)

“So in short, while terms might grant the publisher rights that would permit it to do more than just distribute your material online, the unknown third-party liability risk is too great for them to ever do so,” Friel says.

Don’t forget that the public is watching, too—and a lot of lawyers. Just recently, in Fraley vs. Facebook, five Facebook members filed a class-action lawsuit against Facebook. They objected to Facebook’s Sponsored Stories feature, saying that it violated California law by publicizing their “likes” of advertisers without paying them or giving them a way to opt out.

Facebook settled for $20 million (some of which might be owed to you; see Facebook also agreed to change its privacy settings (so that you can opt out) and notification practices (so that you’ll know beforehand if it introduces a similar program).

In the end, these agreements do give the big Internet companies permission not just to post your material, but also to do other things with it. (You are, after all, getting free services from them.) But they likely never would.  

The bottom line: those terms of service clauses sound scarier, to laymen, than they probably ought to be. The big free services may have lawyers—but we have them, too.