The MPAA isn't the judicial branch, they don't get to be a judge and jury in these cases, they are the plaintiff. Nor are they the legislative branch, if they want to write a law, they need to buy off their congressman like they always have before. And the ISP isn't a police force, they are a witness and vendor to the defendant. If the MPAA wants to enforce penalties like this, use the legal system that already exists rather than acting like the mafia and enforcing their own laws with their own judge and their own police force.
Regardless, I don't see what reason the ISPs would have to work with the MPAA, it's against their financial best interest to eliminate consumers. And it's against the better interest of society to have laws that permanently cut off individuals from the internet, this has become a basic necessity in modern life, not unlike electricity made its transition to necessity in the last century. Anyone that cannot legally use the internet would be much more likely to be unemployed, possibly homeless and a burden on the local society.
If an ISP chooses to enforce these policies, they should immediately lose any local monopoly on providing internet service, open up the area to competition, possibly municipal internet. And ISPs should become liable for denial of service for any reason that is not legally recognized and where an individual was never convicted of a crime. It would be nice if the government found a few laws that the MPAA violated just for attempting to get a policy like this through, discrimination against individuals, anti-trust, extortion, etc.