The Cap-17 law is the rule that placed a ban on late-teen unwinding. Whereas teens from the age 13-18 were once eligible for unwinding, the Cap-17 law lowered the age limit, dictating since then that teens over 17 can no longer be unwound.
The bill gained widespread public recognition Cap-17 after the notorious Happy Jack Harvest Camp revolt, when clappers attacked the camp. The campaigning for its passing became particularly effective when the tithe turned "clapper-who-didn't-clap" Lev Calder became famous, and after Cyrus Finch testified. Apparently, it made people realize that even a seemingly perfect child became a clapper in a burst of rage, and that the boy chose not to clap in the end.
At the same time, however, the Cap-17 law also had a lot of negative consequences. Several of these consequences include a shortage of Unwind parts, which in turn led to a surge in the activities of parts pirates and black market dealers. The price of Unwind parts also soared. Also, this led to the proposal of numerous other unwinding laws, such as the Parental Override Bill, prisoner shelling, and voluntary adult Unwinding.