Immune to bad weather and disease, laws are perhaps Louisiana’s most reliable crop, with fresh statutes sprouting by the hundreds each year regardless of the state’s political climate.

Some laws, such as the ones forbidding murder, possess an infinite shelf life, maybe tweaked, but never to be repealed. A fraction of statutes, though, expire at the hands of state and federal Supreme Court justices. These laws, ruled all or partially unconstitutional by the high courts, become essentially unenforceable.

Yet in Louisiana, some invalidated criminal laws — from an anti-sodomy law to one creating the crime of defamation — remain on the books for decades even after being ruled unconstitutional. That places law enforcement agencies in the awkward position of arresting people for a violation that, whether they know it or not, prosecutors can’t and won’t pursue.

Wiping unconstitutional laws from the state’s law books is the responsibility of the Legislature, said Paul Baier, a constitutional law expert and professor at LSU’s Paul M. Hebert Law Center. And neglecting that duty creates confusion for law enforcement agencies, he said.

“Moreover, it causes the argument, ‘Well, it’s still on the books, so we’ll go ahead and enforce it,’” Baier said. “The police are in that bind: a rock and a hard place.”

In the near future, though, that hard place could soften thanks to a move by lawmakers during the most recent legislative session.

Legislators ordered a comprehensive review of state laws to be completed in search of any statute that has been declared unconstitutional by a final court judgment. The reports, to be done biennially by the non-partisan Louisiana Law Institute, will recommend to lawmakers whether to repeal or revise any laws discovered to be unconstitutional.

The researchers are not far along in the review process at this point, but they’ve already uncovered a number of laws that need closer examination, said Mark Levy, coordinator of research at the law institute.

“We’re still in the gathering process,” Levy said.

A few of the laws deemed at least partially unconstitutional that the institute will likely review include the prohibition on sodomy between consenting adults in private quarters and another derided by opponents as a “driving while Latino” law, both of which have come under scrutiny in recent years.

Other laws include one against “drug-traffic loitering,” which essentially makes it illegal to be present anywhere drugs are known to be dealt. Another example is Louisiana’s law banning criminal defamation, which came into the spotlight this past week after it was revealed that the Baton Rouge Police Department conducted an investigation into a possible violation of the law earlier this year. Parts of that law have been found unconstitutional by various courts over decades.

No one was arrested in the defamation case, but police defended their investigation, saying they would enforce the laws on the books.

However, some Louisianians have been arrested for alleged violations of other laws after a high court ruled at least portions of the laws unconstitutional. This has included men arrested for violating the “crimes against nature” law banning sex between gay people and people stopped under the “driving while Latino” law that effectively blocked immigrants from driving without documents proving their legal status in the country.

Assumption Parish Sheriff Mike Waguespack, president of the Louisiana Sheriff’s Association, described arresting anyone for an alleged violation of an unconstitutional law as a waste of time and resources.

“If it gets to the DA’s office and they’re going to throw it out, then why go there?” Waguespack said.

It’s unclear exactly how many criminal laws have been deemed unconstitutional in Louisiana over the years, although the list is thought to be notable considering the hundreds of laws passed annually and the numerous rulings deeming laws unconstitutional every year.

Pete Adams, executive director of the Louisiana District Attorney’s Association, said many such laws are harmless because in most cases policing agencies choose not to enforce them. It’s only when law enforcement make arrests on violations ruled unconstitutional that the dusty laws become an issue.

In addition, complications arise when the laws aren’t indisputably unconstitutional.

“When portions of the statute are unconstitutional, there’s a possibility that those portions could be separated and excised,” Adams said. “And that makes it more difficult for lawmakers to take a position that might be misunderstood.”

Albert Samuels, a political science and civil liberties professor at Southern University in Baton Rouge, said it’s important to remember that the courts do not operate in a vacuum.

“The courts don’t have a Gestapo or a posse that goes around enforcing their decisions,” Samuels said, meaning the courts must rely on the other branches of government to implement their decisions.

Samuels said failing to repeal clearly unconstitutional laws, such as the portion of the state’s “crimes against nature” law ruled unconstitutional by the U.S. Supreme Court more than a decade ago, puts law enforcement agencies in a thorny position.

In the crimes against nature example, East Baton Rouge Parish sheriff’s deputies from 2011 to 2013 arrested gay men in sting operations at public parks, even though most of the men had only agreed to have sex at private homes. Not long after The Advocate publicized the practice, the Sheriff’s Office apologized for the arrests and vowed to stop enforcing the unconstitutional law. A legislator proposed a bill to repeal the law, but state representatives eventually voted resoundingly to let the unenforceable law stand.

Samuels, the Southern professor, said such decisions defy logic.

“You’re essentially being asked to enforce a law that is actually illegal itself,” Samuels said. “... And that’s sort of a perverse position to put a police officer in.”

Follow Ben Wallace on Twitter, @_BenWallace.