My husband died in March. I plan on filing jointly and would like to claim his son as a dependent also. I believe it is my right as this would have been his fathers year to claim him via court. His mother insists that I have no legal rights since the father was incapable of contributing towards his sons support for part of 2010 and 2011 and says she will be claiming son. I should also note that the child lives with his mother full time. Should I claim him anyway?

No, you can not claim the child.
Only the custodial parent can claim the child.

Are you sure? She agreed that the father could claim his son every odd year. This is his year. It is in the court papers I have right here. He was still alive for part of 2011. This doesn't seem right to me.

Pandorah34:

The divorce decree is a legal document that invokes legal and contractual obligations, but YOU are NOT a party to those obligations. Your deceased husband's rights and obligations did NOT transfer to you on his death. Note that I am NOT a lawyer, but this is my understanding of the law in this case.

It would be better if you posted your question in the LAW forum and get an opinion of an attorney who practices in Texas.

Noncustodial parent can claim the child only if the custodial parent signs a release form 8332. If noncustodial parent claims a child, she/he will not get earned income credit or child tax credit for claiming the child. Noncustodial parent will only get exemption deduction.