Maryland and Arkansas are both members of the Drivers License Compact (DLC) so if your husband pleads guilty and is convicted of the offense of failure to obey a traffic device in MD the courts will report the traffic violation back to your home state of AR.

Arkansas driving records are governed by Arkansas code section 27-50-901. Here it states that the AR Office of Driver Services of the Revenue Division of the Department of Finance and Administration shall establish and maintain a central driver's records file on every driver who receives a conviction for a moving traffic violation while operating any motor vehicle subject to registration for highway use, whether such conviction occurred within this state or in another state.

So it would appear that the Maryland traffic violation will be recorded on your husband's Arkansas driving record. He will need to check with the AR DFA to see if points will be assigned. If so according to the Arkansas' Administrative Point System it appears a failure to obey a traffic signal is normally assigned 3 points.

To read more about the DLC you can read through AR code section 27-17.