I'll defer to the wisdom of those more familiar with admissions at "normal" colleges, but my understanding is that Early Decision is a committment that you will accept admission to that particular school, and no other. It is not "binding" that you will attend that school, but merely that you won't attend anywhere else.
Early Decision is a "handshake" and not legally binding. There is no legal recourse a university has to a student who made an "early decision" and ultimately decided to attend another school. I know of no such legal case where a university even pursued such action - because I'll bet it happens with a certain degree of regularity.
On the other hand, accepting an offer to attend a college, and putting a deposit down, could be a binding commitment.
Binding in that you forfeit your deposit. It's like earnest money when you make an offer on a house. If you end up backing out of the deal and choose not to buy the house, you forfeit your earnest money. That's the understanding.
Again, I will defer to those smarter than I am, but would expect that effective counsel for a college could put an end to those accepting multiple offers by drafting the acceptance in a way that it is a binding commitment to attend for 4 years.
Even athletic scholarships are only good on a year-by-year basis. People say that they got a "4 year scholarship" - but that is hardly ever the case. The scholarship is renewed one a year-by-year basis. There have been instances when an athletic program has terminated an athlete's scholarship without cause. In other words, the student wasn't involved in any disciplinary action and had no academic problems. The only "problem" is that he either got injured or ended up not being as talented of an athlete as they originally thought.
We visited a large university with ED. If you applied ED and were accepted you had 30 days to make a deposit and signed something that you wouldn't accept anywhere else.
Still, no legal action is ever taken. Remember, we're talking about this in the context of MILITARY scholarships. We have an all-volunteer military. Despite any "agreement" a student may make to any institution (I'm talking about ROTC or a service academy), the candidate can back out at any time. Of course, once you're sworn in, that changes. Now you're in the military!
A lot of it comes down to integrity also. It's not looked well upon to accept at two schools or, as in another thread, accept an appointment at a SA and also put a deposit down at Plan B school) unless you've made it clear to Plan B school). Some schools will even rescind their acceptance if they find out.
I totally disagree that there is something unethical about making a deposit to your Plan B school when your intent is to attend a service academy. There are things that can happen that are beyond your control that can prevent you from showing up on I-Day. You break a leg, for instance! You needed surgery two weeks before I-Day because of appendicitis. Now what?
In fact, both my sons (2013 grads) had their deposits in for the University of Tennessee (Knoxville) and
still attended the Naval Academy. We lost the deposit. No big deal! I'm sure UT was glad to have our money.
I know of a kid who was a recruited baseball player for the Naval Academy who could not attend because of a rotor cuff injury he suffered his senior year in high school. So, he went to another university. There was the understanding that he should reapply to the Naval Academy after his freshman year and they would accept him. The coach still wanted him. So he
did reapply. And he
was accepted. And just weeks before I-Day, he was involved in a car accident that reinjured his shoulder. He couldn't attend the Naval Academy. Pretty sad story. He gave up on his service academy dream and continued on (and graduated) from the civilian university.
In fact, I would encourage every service academy candidate to maintain a Plan B option up to the final moment - even if it involves forfeiture of a deposit.