RCW 46.37.100
RCW 46.37.210
or
RCW 46.37.150
all state:
"white or amber light"
this is where you argue that "yellow headlights can be called amber".
so, I'll adjust my statement:
99% of you guys that have yellow headlights, do so because of 3000K hids, and those most definitely are illegal. Hologens behind yellow film is just fine.