Cops have tough, thankless jobs and are constantly under the microscope which can be very stressful. In addition traffic stops are one of the most dangerous things they do on a regular basis, there's no way to know what will happen when they walk up to the window.

I'm not necessarily excusing the officer from his actions, or saying that there aren't "dick" cops out there; but I do think too many people assume a significant portion of policemen are egomaniacal power hungry a-holes. I don't envy a police officer's job, they are expected to be as sweet as an angel and as tough as a soldier and deal with a-holes all day.

Even cranky grandmothers need a good tazing sometimes to set things straight