Cops are people; one presumes they have consciences just the same as anybody else. If the laws are unjust, they should find an honest job rather than cowering behind the "just doing my job" excuse.
I agree with this. I have a number of LEO friends who say they will not enforce unjust firearms laws. Whether when the time comes they will really drop their shields and walk away or not remains to be seen, but it is easy to claim that.