Since this thread is about what I do for a living, I'll chime in.
The Federal gov't can be sued for negligence committed by Federal employees. If a post office truck runs a red light and broadsides you, you can go after the gov't.
But, cases against the gov't proceed under what is called the Federal Tort Claims Act, and the procedure is significantly different than a normal civil lawsuit that doesn't involve the gov't. First and foremost, there is no right to a jury trial. The case is tried in a Federal Court to a Federal Judge who sits as the sole trier of the facts and he/she applies the negligence law of the particular state where the accident happened. Since Federal Judges are among the best and the brightest in the whole legal system, and since emotion on the part of ordinary people on a jury plays no part in the proceedings, the gov't wins more than its share of these cases when it's a close call as to whether the Federal employee was negligent. And, of course, the employee's own money is not at stake.
Most states have some sort of scheme to share responsibility between a plaintiff and the defendant, so that if the plaintiff bears some of the responsibility for the accident, let's say 30%, his award is reduced by that 30%. Federal courts apply the law of that state, so there is no uniform "fault sharing" across the country in these FTCA cases.
I had just such a case about 20 years ago. A CFI was out with a student, doing night landings at about 11 PM. They were returning from practicing at a rural airport, headed toward the large, airline airport where the flight school was based. While on an extended base leg in the pattern, approach control changed their landing runway. When they were turned over to the local controller in the tower cab, he cleared then to land, saying "Do you have the 737 on final? The little airplane affirmed that they had the airliner in sight. The controller then said, "OK, keep it in tight behind the 737, I have a Falcon at the marker smoking up your tail". He also failed to give the mandated " Caution wake turbulence " warning.
The little airplane hit the wake of the 737 about 100 feet above the runway, and rolled 90 degrees to one side, then 90 degrees to the other side, but luckily impacted the ground flat, drove the gear up thru the wings of the Grumman, breaching the fuel tanks, and starting a bonfire. Thankfully and miraculously, no one was seriously injured. As the fireball careened down the runway, the student pilot, a big guy, opened the canopy, and literally threw his 10 year old son, who was in the back seat, out onto the ground. The student and the CFI got out the moment the Grumman stopped sliding. The only injury was a slight burn on the top of the kid's hand. The Grumman came to rest at the airline gate area, under the wind of another 737 and one wing of that parked 737 was totally destroyed in the fire. Total damages to the owner of the parked 737 were about $6.5 Million, for repairs that took months, and loss of use of the airliner for those months.
So, we sued ATC for controller negligence on behalf of the airline that owned the parked 737. Remember that this was a night flight, making it nearly impossible for the CFI and student in the Grumman to see the touchdown point of the first 737 landing ahead of them, and plan their own touchdown point beyond that of the landing 737. They were obeying the controller's instruction to keep it in tight.
The court held, properly I think, that the CFI was 30% responsible, and the controller was 70% at fault. I certainly can't go into all that took place in a 4 week long trial, but we have to remember that while a pilot can refuse to accept a clearance, the truth is that most general aviation pilots view ATC as the police of the air, and are very reluctant to tell a controller to go pound salt.
Anyhow, just a war story of how it works in real life.
Jerry E.