You're stopped at a red light in the right hand turn lane of a one way street. Can you turn right into the one way cross street assuming you don't impede any drivers on that street? TIA

Yes it's legal. How much was the ticket they issued you?

Seriously though, at regular two way intersections I notice sometimes they post signs that say something like "wait for arrow" with a picture of a right turn arrow, and sometimes that is in Thai only. The BIB will then wait down the road to do you for turning across traffic on a green light before the green arrow appears. Also, sometimes turning is restricted during certain times of day.

Point being, if you got done for doing what you described in your post, check the intersection for signs. It might be posted.

It's also not uncommon for Thai police to just make shit up completely. If you got a ticket for something that seemed legal, that may be your answer. I'd like to know what the cop said, if anything. There are certainly a lot of laws on the books here that don't seem to make sense so I wouldn't be surprised if it was illegal.

Having worked traffic enforcement in the west, I often struggle to understand the rational for traffic design here. It just seems to make a bad situation worse.