Enforcement isn’t about big government or small government. It’s about whether government works and who it works for. Last year, five of the world’s biggest banks, including JPMorgan Chase, pleaded guilty to criminal charges that they rigged the price of billions of dollars worth of foreign currencies. No corporation can break the law unless people in that corporation also broke the law, but no one from any of those banks has been charged. While thousands of Americans were rotting in prison for nonviolent drug convictions, JPMorgan Chase was so chastened by pleading guilty to a crime that it awarded Jamie Dimon, its C.E.O., a 35 percent raise.

To be fair, weak enforcement is sometimes a result of limited authority. Despite the company’s history of egregious safety failures, for example, the former C.E.O. of Massey Energy was convicted only of a single misdemeanor in the deadly Upper Big Branch mine disaster that killed 29 miners in West Virginia in 2010, because federal mining laws are too weak. It’s on Congress to stiffen such penalties.

But in many instances, weak enforcement by federal agencies is about the people at the top. Presidents don’t control most day-to-day enforcement decisions, but they do nominate the heads of all the agencies, and these choices make all the difference. Strong leaders at the Environmental Protection Agency, the Consumer Financial Protection Bureau and the Labor Department have pushed those agencies to forge ahead with powerful initiatives to protect the environment, consumers and workers. The Special Inspector General for the Troubled Asset Relief Program, a tiny office charged with oversight of the post-crash bank bailout, has aggressive leaders — and a far better record of holding banks and executives accountable than its bigger counterparts.

Meanwhile, the Securities and Exchange Commission, suffering under weak leadership, is far behind on issuing congressionally mandated rules to avoid the next financial crisis. It has repeatedly granted waivers so that lawbreaking companies can continue to enjoy special privileges, while the Justice Department has dodged one opportunity after another to impose meaningful accountability on big corporations and their executives.

Each of these government divisions is headed by someone nominated by the president and confirmed by the Senate. The lesson is clear: Personnel is policy.

Legislative agendas matter, but voters should also ask which presidential candidates they trust with the extraordinary power to choose who will fight on the front lines to enforce the laws. The next president can rebuild faith in our institutions by honoring the simple notion that nobody is above the law, but it will happen only if voters demand it.