Actually, no I wouldn't. It's no different from stopping a drunk from driving or any other person who is a danger to society. The LEO's are glad to see citizens step up and do something when needed. You have to have the law involved from the get go if at all possible and at least asap. Other than that, happens all the time. Drunks, diabetics, epileptics, other medical problems, criminals, what have you. What you said isn't true at all.
I get on the phone, tell dispatch there's someone who is unable to control a 17 ton truck and is all over the road. He pulls over, I pull in front, the coworkers pull in back, and we wait. There's multiple witnesses and video evidence. My position is secure. At that point the driver of the truck cannot leave anyway as he has to talk to the law and he would be informed as such. Your comments about being in jail, serious charges (civil and criminal), bodily harm, ambulance, being arrested, coroner, are just sensationalistic and a joke.
I'm a LEO and can tell you without a doubt that it is illegal to block someone in and not let them leave. The prosecutor may not press charges against you but the driver of the other vehicle would certainly have a civil case against you.
As a LEO, I do not advise citizens to take enforcement actions. All of my colleagues have the same opinion because to do otherwise means that you are essentially directing a civilian to act as an agent of the law and are opening yourself up to a lawsuit, either by the civilian or the person they are acting against.
As for the part about bodily harm, it's SOP for my family that if someone other than a LEO attempts to pull them over, tries to box them in, or otherwise attempts to stop their progress and makes aggressive movements towards them, they are to put the truck in 4-Low and either drive over the person or drive over the car. I've used this tactic both foreign and domestic and the law and prosecutors have agreed with me each time.
In the foreign instance the person acted agressively and tried to block my wife into a parking spot. She perceived it as a carjacking attempt and reversed into their car pushing it out of her way. She also ran over and broke the leg of the driver. Immediately aftewards she called the police, drove to the Consulate, and reported the incident. The back story was that the woman misidentified my wife as a hit and run who hit her car earlier in the week and tried to block her in. Because the woman exited the car screaming and tried to open my wife's door, my wife took prudent action and acted correctly. No criminal charges were filed against my wife although charges were filed against the woman. We were told that we could go after the woman in civil court as well but we declined.
In the domestic instance, it was an attempted truckjacking where the person tried to block in my cousin whle he was driving his semi. My cousin slowed to help a stranded motorist (daylight) but didn't get out of the truck because the passenger of the vehicle was acting strange. After calling in the motorist on his cellphone, two more vehicles arrived and tried to block in his truck. He blasted his horn and when they didn't move AND they exited their vehicles, he just pushed them out of the way, started moving, and called for assistance. In his case, he wasn't charged either criminally or civilly, nor did his insurance pay for their vehicles (1 totalled, 1with extensive damage, 1 with the passenger side ruined). Although the men had weapons in the vehicle and they couldn't prove the attempted carjacking, there were charges filed related to impingment of freedom/false arrest (I don't remember the exact charges).
Anyway, that's a long hijack just to say: If you see someone doing something dangerous in a vehicle, dial 911 and follow them at a safe distance. If you have 2 vehicles, there's nothing wrong with pulling in front and flashing your lights/honking your horn to alert oncoming traffic (but not trying to slow them down or force them off the road). BUT, if you attempt to pull them over or otherwise impede their movement, you will be acting outside of the scope of your authority and opening yourself to possible criminal or civil charges.
