The question you should be asking is how Texas will handle it. Texas has jurisdiction over your son for this criminal matter and they will set the perameters with regards to his bond conditions as well as any post conviction conditions, ie probation. His Texas lawyer is the proper person to get this information from.
Speak with his Texas attorney, and make sure that he/she is an attorney that regularly handles DUI/DWI/OUI cases. He/She should be able to evaluate the merits of the case and give you a better idea of whether or not it is a case worth trying or pleaing out. If it's not a triable case, the attorney should be in contact with the probation department in TX to explore your son's options going forward with regard to any contemplated move to Tennessee. Best of luck.
Joe Higgins
The Law Offices of Joseph J. Higgins III
2277 State Road
Plymouth, MA 02360
***DUI, DWI, OUI and any other information in this response should not be construed to be formal legal advice nor the formation of a lawyer or attorney client relationship.
He will have to confirm with his pretrial bond supervisor that it's okay for him to leave Texas while the case is pending. Assuming it's okay with them, he can move to Tennessee but will likely have to return to TX to complete his DUI case. If he's convicted of DUI and Texas suspends his driver's license then when he moves to TN, TN will also suspend his license if he tries to get a TN driver's license. Each state honors the driver's license suspension of the other state.
It is important that he obtain a Tennessee license before pleading to a Texas DUI. If he does not, he will be unable to get a restricted license in Tennessee. He or his attorney should consult with a Tennessee attorney to discuss this issue so as to avoid being caught in limbo.