Affirmative. You cannot and must not apply Early Decision Binding to more than one school. In agreeing to the EDB accord you are contracting with the law school to attend if they accept you. Obviously you cannot make such a contract in good faith with more than one school. If you did so, you might not actually get sued, but you probably won't get into any law school worth the name.
Some schools (Cornell, eg) have an Early Action Non-Binding--this sort of agreement does not require you to attend, it merely guarantees you early notice of the school's decision. You'll need to read each school's individual policy in order to determine which case it is, but it ought to be quite clear on the application/website.