10 years ago I bought a brand new tandem axle trailer in Texas and brought it back here. It only had one set of brakes. During the inspection by WSP it was brought to my attention that WA state law is brakes on both axles. They passed it but strongly recommended I get brakes on the 2nd axle. I think if you buy one out of state brand new you can get away with registering it in WA with only one set, but anything sold new in WA has to have brakes on both. I never did put brakes on that 2nd axle and never had a problem. I sold it a few years ago and as far as I know it still has only one set of brakes on it. The trailer that replaced it has brakes on both axles.
Even though I got away with it, what's the point in not having brakes on both axles? The things are stupid cheap to buy loaded backing plates and put drums on. Had I known they were that cheap and easy to do I woulda put em on the #2 axle on the first trailer when I got it. Cheap insurance.....