Noisy neighbor throws parties daily – how to stop him? And why aren’t the police doing anything about it?

Location: Massachusetts

TLDR: my friend’s neighbor is obnoxiously noisy every day and throwing parties nightly. His normal speaking voice seems to be yelling. Cops called many times by multiple neighbors and nothing done.

More info: My friend is disabled by illness. His parents are in their late 70s and his mom has cancer. Noisy Neighbor (will abbreviate to NN) has been carrying on for 5yrs. NN (40s?) is married with two young children. He started by throwing parties where he would crank the bass up and it would shake the surrounding homes. Even if the party was indoors, you could hear/feel the thumping bass. Parties were anywhere from 10-40 people. NN was spoke to multiple by my friend’s dad. One day the NN and his wife show up on friend’s doorstep and angrily accuse friend’s family of calling the police on them due to racial profiling… It wasn’t my friend’s family that called.

Eventually NN has moved his parties almost solely outside. His built a backyard party hub for his friends. Nightly, there is always about 10 people. They pretty much meet rain or shine. From mid June to Aug this year the NN had a party every night except for 2 nights. The NN and his guests are all yelling and carrying on typically from 7pm-2am nightly. The guests park all down the street, specifically more in front of my friend’s home. They walk through my friend’s yard (even walking right up near friend’s windows), litter beer bottles in the street, and idle in their cars with loud music playing. Twice since these parties started my friend’s parents’ vehicles were broken into. Their neighborhood used to be really quiet and nice until NN moved in.

Friend and his parents call the police on NN all the time. Sometimes multiple times in a single night. If an officer even responds, at best they pull up in front of the house for a minute or two and then drive off. NN also lights a fire pit nearly every night and those are supposed to be illegal in our city. The houses are all close to one another. And the smoke blows into my friend’s house till late at night.

We know that other neighbor’s are calling the police because they show up without my friend having called. Friend’s mom has even gone to the police station to see if there was more that could be done and was told just to keep calling. Friend’s mom has spoken to a couple neighbors and asked their thoughts on NN and so far every one has said the man is too loud; one neighbor from the next street over told friend’s mom that she feels sorry my friend’s family has to live next to NN because even she’s bothered by the noise from where she lives; and one neighbor from several houses down even said, “I wish he was dead” when referring to how much she’s bothered by NN. So we do know that this is a neighborhood wide thing. I have driven to the next street over and I can still hear the neighbor yelling.

Clearly calling the police isn’t helping. This is causing major stress for my friend and his parents. My friend’s stress levels have skyrocketed due to NN and he feels helpless due to being so chronically sick. His mom is trying to get through cancer. His dad helps by calling the police and has been the one to ask the neighbor to be quiet.

What can be done to stop this guy once and for all?