Read the parts of Chapter 4 on Patents.
Read Chapter 5 on Crime.
There is a price for illegitimate DMCA takedowns!
How Bungie tracked this down: torrentfreak.com/digital-trails-how-bungie-identified-a-mass-sender-of-fake-dmca-notices-220624.
There's a penalty for filing false DMCA takedown notices, but Bungie appears to be focusing on other charges as well.
Microsoft tried to patent the BlueJ Java IDE's "object workbench", too, although they backed down.
1. Contesting patents in court is very expensive ($2 million?)
2. Even contesting these patents via a so-called IPR (a special hearing procedure within the PTO) costs an average of $300-500,000.
3. There is no free mechanism for saying "this patent is fraudulent"
4. Supposedly there is a penalty for willfully failing to list all known prior art, but the PTO almost never applies this.