GeoPall

I've heard that it is every graduate student's right to renege and offer before or on April 15th if an institution supports the Council of Graduate Schools Resolution, and indeed the official Resolution reads that way as well. However, I was curious if anyone has reneged on an offer before/on April 15th and suffered any consequences? Such as not being "released" even though, according to the Resolution, you don't need an official release before/on April 15th. What is the worst case scenario? They are mad at you, but they can't MAKE you attend right? Thanks for any advice!