Should a fisherman face 20 years in prison for discarding a few fish at sea? That question is at the core of a statutory interpretation case the Supreme Court heard in November, but it also raises another question: What does “cruel and unusual punishment” mean today?

When a Florida fish and wildlife officer boarded John Yates’ boat, he found a number of fish too small to be legally caught. Before reaching land, Yates discarded three of the fish. To punish him, federal prosecutors used a white-collar crime statute criminalizing the destruction of “any record, document or tangible object” intended to obstruct a federal investigation.

During oral arguments, Justice Antonin Scalia observed that Yates could have received 20 years and asked the prosecutor: “What kind of sensible prosecution is that?”

The lawyer for the government responded that federal prosecutors often do not prosecute such offenses, but when they do, they pursue “the offense that’s the most severe under the law.”

Scalia retorted: “If that’s going to be the Justice Department’s position, then we’re going to have to be much more careful about how extensive statutes are.”

Amen to that. The courts should be much more careful.

Yates received a 30-day prison sentence but is appealing his conviction, claiming that the law known as Sarbanes-Oxley is intended to cover shredded documents, not dead fish. To address Scalia’s question, though, a two-decade sentence for throwing three fish into the ocean would be cruel and unusual.

The judiciary needs to vigorously guard against statutes that allow excessive punishment. Our legislators are human. They are subject to the same vulnerabilities and weaknesses as the rest of us. Our criminal penalties too often reflect the fear and anger triggered by some salient event, not a cold and sober calculus about what harm was caused or what deterrent is necessary.

The problem is that once crime-fighting legislation is passed, it is very difficult to undo. Societal anxiety about crime means that candidates rarely propose reducing criminal sanctions when they are seeking office. As Justice Stephen Breyer puts it, politicians know how to “hold their finger up to the wind to measure popularity.”

Given the stickiness of criminal statutes, the judiciary’s responsibility is to question whether Americans would tolerate the punishment if it were applied routinely to everyone who commits the offense. Any punishment that is tolerated only because it is applied infrequently and unevenly is not one that the Eighth Amendment tolerates.

The Supreme Court’s current approach to Eighth Amendment claims is needlessly obtuse – and results in too little judicial intervention into punishment practices.

This argument is not limited to fishermen who throw grouper back into the ocean. Draconian punishments are repeatedly given for nonviolent drug offenses. For instance, a man in Slidell, Louisiana, received a life sentence in 2011 for possessing marijuana for the fourth time.

There is a nearby area in New Orleans where 20-somethings often possess marijuana and, no doubt, could have been convicted multiple times. We call that drug-ridden neighborhood Uptown, and its population includes Tulane University students, some of whom are the sons and daughters of Louisiana’s wealthiest residents.

It does not take much reflection to absorb the reality that interminable prison sentences for nonviolent marijuana offenses or death sentences for homicides would not be tolerated if they were applied consistently and evenly to anyone – white or black, rich or poor. Most of the people serving excessive prison sentences are among the nation’s poorest and least influential citizens. No powerful lobby presses their plight. And often the loss of franchise is a cost of their incarceration. Nobody stands up to protect them.

While the criminalization of marijuana possession may have the broadest impact, the haphazard application of the death penalty makes the deepest cut. A majority of states have abandoned the death penalty in law or in practice.

Eighteen states have legislatively abolished the death penalty. Six more have either not imposed an execution or not sentenced anyone to death in a decade. The governors of Washington and Oregon have declared formal moratoriums on executions. And most Americans live in a place where no one’s been sentenced to death in years.

We live in a nation that incarcerates a larger percentage of its population than any other industrialized country. We have emptied our public hospitals, mental health wards and drug treatment facilities and filled up our prisons. We treat people who commit crimes with a brutality that would be incomprehensible if the people who suffered under the burden of this system were the loved ones of the people who make and enforce our laws.

This is a judicial failure. If a punishment wouldn’t be tolerated if applied regularly and evenly, then the power and responsibility to ensure that it is not imposed at all rests with the courts.