Are they allowed to take MY money in MY account?

About two years or three years ago my mother opened up a bank account for my brother, herself, and I. Because my brother and I were too young to open the account ourselves, we had to have a joint account. With this joint account, she could put money in, take money out, etc., but the account is mainly in my name. On this Tuesday (July 30, 2012), I found out my account was frozen by the State of Virginia. My bank never contacted me about this in fact noone did. My mother came home and said that my account may have been frozen, so I called. On this Wendsday (July 31, 2012), my brother and I check our accounts and we see $0.00. We call and they say that the state of Virginia has frozen it and taken all of the funds that WE worked for because of a bill my mother has not been able to pay. My point is, this account is MY account, NOT my mother''s. I worked for the money, NOT my mother. So why have the seized all of my funds? Are they allowed to do so? Is this grounds to file a lawsuit?