Despite releasing a comprehensive and remarkably radical criminal justice reform agenda in 2015, Senator Bernie Sanders was accused throughout his presidential campaign of being insufficiently concerned with the topic, and of habitually changing the subject to economics. The reality is that Mr. Sanders has the clearest insight into the connections between criminal justice issues and economic inequality of any major politician today. And nowhere, perhaps, are those connections more obvious than in the instance of cash bail.

In late July, Mr. Sanders introduced legislation that would end cash bail on the federal level. “Cash bail” is the current bond system in which people arrested for even low-level offenses are detained pending trial — unless and until they pay a fee. The fees are often arbitrary and often beyond people’s means ($3,000 for allegedly stealing a backpack, $10,000 for a bicycle), leaving the poorest arrestees locked up, sometimes for years, without being convicted of a crime.

Under this system, freedom comes with a price tag, and those who can pay it get to walk while the rest languish in the United States’ bloated prison system. Citing a statistic showing that over 400,000 people are in jail simply because they can’t afford to pay bail, Mr. Sanders called for the end of “modern day debtors’ prisons.”

Mr. Sanders’ bill is more radical than one proposed last year by two of his colleagues, the Democrat Kamala Harris of California and the Republican Rand Paul of Kentucky, which sought to reform but not eliminate cash bail. In completely prohibiting “the use of payment of money as a condition of pretrial release” on the federal level, the Sanders bill turns one of Black Lives Matter’s most broadly popular demands directly into legislation.