insular system = isolated system?

Yes, it's similar to 'manipulated' but the feeling inclusive in 'rigged' is that it was set up to perform in the manner that the ministry wanted.

Imagine a roulette ball that has a magnet put inside it and the roulette table has a switch where the casino can throw a switch to cause certain slots to reject or accept the roulette ball. That's an example of how something can be rigged to make sure of the outcome.

Or in horse racing, some horses are given drugs that will cause them to run slower. That's a rigged race.

A "rigged" trial would be one where the outcome was already determined to be in someone's favor before it even went before the court.

Thank you both.

insular system = isolated system?

Not isolated but insulated. Imagine a room in a house in a cold climate. One that is isolated, ie. has no walls that touch the outside is isolated [from the cold], no direct contact with outside temperatures so there is no appreciable heat loss.

An insulated system still has connections, be it direct contact with the cold [or, in your case, contact with citizens] but with the insulation, it can moderate those connections, control those connections to some degree.

Good usage.

Thanks.

“The No. 1 mission of the court is to protect the interests of the ministry,” Mr. Zhang said.

The court system, according to Mr Zhang, insulates the ministry from citizens when things get too serious.