For those of you who were bored and actually read the california vehicle codes from start to finish, “speed traps” (if you are using the term correctly as defined by california vehicle code) are illegal.
These sections of the CVC relate directly to the use of “speedtraps” within California:
40801 Speed Trap Prohibition
40802 Definition of a Speed Trap
40803 Speed Trap Evidence
40804 Testimony Based on Speed Trap
40805 Admission of Speed Trap Evidence
40808 Speed Trap Evidence