Traffic police vs rule of law?

Dear Forum users. I have a very important question that relates to the protection of rights of drivers. Hope nobody will face such thing.

My father in law just recently got hit from behind his car by a huge truck, He was about to turn right, and had his left turning lights turned on with the speed of 10km/h but then suddenly he was hit from behind by the truck coming with higher speed so that he got several injuries and had been transported to hospital and got 5 sutures on his head. The police officers came to hospital and intimidated him not to disclose the information about this accident with human casualties involved, but rather they want him to say that it was only between cars. The purpose is that police does not want the increase of statistical numbers of car accidents in their area or prefecture. Otherwise they intimidated him to take his drivers license for several months.

My question is how can we protect our right in this case, the insurance companies are not willing to help us because the revenue will not be too high for their business.

I thought Japan is the rich developed country, where people can be protected by the law against arbitrary rule of traffic police and an obvious lie of the responsible person.I thought Japan is far from African or Latin American countries, where there is no functioning rule of law. Where everything is just on the paper. Is there any way to protect our right and solve the question with fairness. The driver of the huge truck that hit the car from behind had no injuries and continues to enjoy his life feeling no guilty conscience and police helps him too, owing to their own interest.

Is it a normal thing in Japan? Is it ok, that police goes against people instead of protecting them? I AM TOTALLY AGAINST SUCH PRACTICES AND SEE NO CHANCE AS TO FIND CONSULT WITH THE LAWYER IN ORDER TO START A LAW SUIT AGAINST THE POLICE AND THE GUILTY DRIVER!

I need a good advice, because if such practice becomes a normal thing, then that means nobody can protect him/herself in such situation.

Thank you for your contributions in advance.

Frankly, I can't help to feel that there might be more to the story. But in case there isn't, I think it would be very noble of you to fight for the right cause and seek the advice of a lawyer.

Thanks for the opinion! I think this is the only way.

He was turning right but had his left blinker on?

Any case, call a lawyer, no one here is sound to give legal advice.