This crap happens all the time in MD.
I got pulled over on the bike to check for my license once. I filed a formal complaint, because all the dickbag did was made me late to where I was going.
EDIT: One night while driving back from the community college (about 9pm) I was pulled over in the car for using a turn signal to announce my intention to exit a roundabout. The PLAINCLOTHES state trooper got out of his UNMARKED car and asked for my license and registration. I asked to see his badge, and he hesitated. It took him a couple seconds to pull the badge out of his pocket. After he ran my registration, he came back and asked to take a look in the trunk. I informed him that I didn't consent to a search of my property. He said alright, and went back to his car. He came back in a couple minutes, handed me my registration and license back and gave me a stern verbal warning about excessive signaling. I got his badge number, and then when I got home I filed a formal complaint with the state police.
Another time, I was pulled over for "going too fast." I asked the officer how fast I was going (knowing I was going the speed limit, and I had my winter tires on, so I should have been going 1.8% slower) he said he "visually estimated my speed at about 5mph over." When I asked him how fast the car that just went by us was going (he pulled me over on a four-lane divided highway) he said he didn't know. He ran my license and registration, and brought it back after he wasted approximately 20 minutes of my time, and gave me no ticket at all, just a warning to not speed, and that in his experience people with radar detectors tend to speed more. I asked him when signal detection equipment was outlawed in MD, and he said "it's not to my knowledge." I asked him if I was free to go, and for his badge number, and filed a formal complain when I got back home.
One more time, I was driving home from my parents house, going the speed limit, some guy was tailgating me, so I took my foot off the gas. Keep in mind, this was a 30mph zone, and I had been doing exactly 30mph. He flashed his brights, and I got down to 25mph. He then decided to pass me (double yellow, school zone, almost 10pm). After passing, he cut over extremely close to my car, so I flashed my brights, and signaled my horn as I slowed down. He then slammed on the brakes. A cop was sitting on a side street, and saw some part of this, and apparently raidioed in a stolen car. We got to the red light, and the guy who passed me stopped, then jumped out of his car, and ran to my car, banged on the window as the cop rolled up with lights on.
At this point I was on my horn almost 100%, and was unable to back up to GTFO of there, because someoen was behind me. The cop jumped out, drew his service weapon, and instructed the guy to get back into his car. The guy got back into his car, and the officer reholstered his weapon, and walked up to the guy's car, got license and registration, then came to my car and got my license and registration.
I told the officer (who I just saw draw and aim) that my wallet was in my backpack on the back seat. He said "alright," and gave no other signs that he was going to say anything. I said "I'm going to get it" and waited for him to give acknowledgement, then reached back to get it. I gave him the license and registration, then waited 15 minutes for him to come back. He came back, asked me what happened, I explained, then he went to the guy in front, talked to him, came back to me and said "we're going to move you guys out of the intersection, just pull up and turn on the road on the right" So we did. He came back and talked to the guy in front a bit, came talked to me a bit, got indignant with me, told me that he thought my car was stolen, and the lights and horn were the alarm. He told me that I needed to calm down, and that I was a vigalante for "taking matters into my own hands." I just said kept quiet and let him get everything out.
He went back to his car, and his buddy walked up to my car, looked in the windows (thought I couldn't see him all dressed in black/dark blue) then looked in the other guy's windows. The cop came back, gave the guy in front of me his license and registration back, then the guy drove off. The cop came back to me, gave me a ticket, my license and registration and told me how he didn't see what happened, so he "could only give me a ticket for following too closely, using my brights, and using my horn." I let him explain everything, then he told me that he talked to the lady behind both of us, who saw the whole thing. I just kept my mouth quiet, and made a mental note of the supposed witness. I'm taking this one to court.