Who is at fault Car a is turning left car b in the approaching lane waves car a to cross in from of car b car a is hit by car c is that is coming up in the other lane parrall to car b .?

Answer 1

This sucks but:

Both driver B and and Driver C

Driver B took responsibility for all involved when he signaled car A to go.

Of course Car C is At Fault as he did not slow down to see why car B was stopped.

I know this sounds wrong but blame the lawyer that convinced a jury this is how it should be.

Another View: Driver A is at fault because he has the responsibility to make the turn in safety REGARDLESS of any unauthorized signals from any other vehicle on the road.

Signals from another driver to proceed carry no official weight and do not absolve Driver A from making the turn with regards to all other traffic travelling in the opposite direction.