What happened
Clinton signed the crime bill in September 1994 after a bipartisan legislative push, explicitly positioning Democrats as tough on crime after a decade of Republican attacks on the party as soft on it. The bill funded 100,000 additional police officers, allocated $9.7 billion for new prison construction against $6.1 billion for prevention programmes, and imposed federal "truth-in-sentencing" incentives that pushed states to require violent offenders serve at least 85% of their sentence.
Its three-strikes provision mandated 25-years-to-life sentences for a third felony conviction — a category broad enough to include non-violent property and drug crimes in some cases, and one that sent people to prison for the rest of their lives over offences as minor as theft when combined with a defendant's prior record.
The incarceration trend predated the bill — it had been rising since the early 1970s — but the 1994 act poured federal money and legal architecture into accelerating and locking in that trend for a generation, disproportionately affecting Black communities that were already over-policed. It remains one of the most consequential pieces of domestic legislation any Democratic president has signed, and Clinton himself later said parts of it "made the problem worse."