My son is almost 3 and his father within the last year has been able to see him a few times a month, he does pay support... but has actually violated our court order for visitation several times. He decided today that he wants to file my son on his income taxes!! How is this even possible?? He said he has the right to now, but I believe because my son is with me most of the year he sohuldn't be able to. Can somebody PLEASE help me find the answer? Is he able to file my son on his income taxes without actually having him the way I do?? I don't think it's right!

He can try but it will be rejected. The IRS has come out with new rules and if they live with you most of the time then he can not legally deduct them with exceptions
A) You have signed over the deduction to him.
B) You will not be making a federal income tax return.