Check with your local DMV/STATE DOT office to see if you are required to have Electric brakes on your trailer and what the local laws pertaining to trailer brakes might be.
Here in Virginia if we are required to have electric brakes then we also must have a working brake controller along with a Break-away switch arrangement on the trailer with a working 12VDC battery setup in the event the trailer becomes disconnected while being towed on public roads. This arrangement applies max BRAKE voltage to stop the run-away trailer... This is an annual inspection item for us here in Virginia...
I suspect all of this varies from state to state.
Roy Ken