If you have a union or other contract that is being breached, you talk to your union rep.
Otherwise, if you like you can *politely* ask for a raise. If they give it to you, fine. If they don't, you either suck it up or you find other work that will pay you more.
There is nothing in the law that says all employees in the same job must be paid equally - the law says only that IF employees are paid differently, the differences cannot be based on race, religion, gender etc. How long you have been in the job is not a characteristic protected by law. Due to market compression, it is (sadly) neither uncommon nor illegal for newly hired employees to be paid more than those who have been in the job a while.
STRONGLY recommend that if you ask for a raise, you do it on the basis of your own value to the employer and NOT based on "so-and-so gets more". THAT can get you fired. Legally.