I’ve always said I’d much rather speak to a roomful of cops than a gaggle of lawyers or politicians.

But I may have to rethink that. Lately, when a certain subject comes up, some cops I talk to sound like lawyers and politicians.

Twice a year, I get invited to speak to a gathering of about 20 police commanders who come together for management training. During a weeklong session, they listen to about 10 speakers—including me.

I go with the intent of talking about media and how to improve the relationship between cops and journalists. But inevitably, I wind up talking about something else: whether local police should assist Immigration and Customs Enforcement (ICE) in the enforcement of federal immigration law.

As the son of a retired cop who spent 37 years on the job, and someone who has studied, reported on, and written about the immigration debate for three decades, my answer is an emphatic: “No!”

This has always been a hot topic in both the law enforcement community and the world of immigrant advocates. It was controversial way back in the early 1980s when the police officers in my hometown of Sanger, California, were roped into helping Border Patrol and Immigration and Naturalization Service (INS) agents raid a string of bars looking for illegal immigrants. The federal agents grilled bar patrons about their legal status.

But it was local police officers who cordoned off the area and maintained order. After the Border Patrol made a couple dozen arrests, they were on their way. But for years after that, local policing was more difficult because the immigrant community was distrustful of anyone wearing a badge. Victims didn’t report crimes, witnesses wouldn’t testify. Community relations were harmed. Crime went up.

Today, politicians in both parties carelessly toss around the word “sanctuary”—as in “sanctuary cities” or, in the case of California, one of the nation’s first “sanctuary states.” Democrats tell Latinos that they’re compassionately offering protection to the undocumented, while Republicans insist that a declaration of “sanctuary” rewards lawbreaking.

No one is telling the truth, the whole truth and nothing but the truth.

The relationship between local police and federal immigration officials has been a roller-coaster ride over the last 40 years. In the 1980s, they were too cozy. This led to laws in the 1990s that intended to establish some church-and-state separation. Then came the terrorist attacks of Sept. 11, 2001—which revealed the dangers of one hand of law enforcement not knowing what the other hand is doing—and “cooperation” became the new catch phrase.

The INS was eliminated, and replaced by ICE. And the relationship between the jurisdictions got cozy again. For instance, ICE agents had virtually unrestricted access to county jails, where they could fish for suspected illegal immigrants without having anyone’s name on a warrant—or, in fact, any warrant at all.

Now, in states like California, lawmakers are re-establishing some distance between the locals and the feds. In 2017, in response to the election of Donald Trump and his threat to use a “deportation force” to crack down on “sanctuary cities,” Democratic lawmakers in Sacramento passed SB 54. The authors titled it the “California Values Act.” But most people call it the “sanctuary state bill.”

The idea was to prohibit the use of state and local resources—including personnel and facilities—to enforce federal immigration law.

Democratic Gov. Jerry Brown, a centrist on law enforcement issues, threatened to veto the bill unless language was added to allow for more cooperation between local police and federal officials. For instance, Brown wanted to make sure that ICE still had access to county jails—but only if they had a warrant with a specific individual’s name on it. The amendments were made, and the governor signed the bill into law.

In the Golden State, and around the country, everyone had a strong opinion about the measure, but not many people seemed to have a clear idea of what it allowed or prohibited. Most people believe the law gives away the store.

Apparently, as I would learn, that view sometimes extends to the local police officials I find myself talking to.

Here is what I tell them:

I think the whole “sanctuary” thing is a myth. It’s the unicorn of the immigration debate. It doesn’t exist. There is no city or state in this country where federal law doesn’t apply and where federal agents can’t go to enforce it.

Ironically, the Trump administration—which claimed that SB 54 prevented the federal government from enforcing immigration law—made my point for me when it announced, at one point, that it was going to crack down on California by sending hundreds of additional agents to the state to enforce immigration law. In other words, the feds were going to do the very thing that they had claimed the state prevented them from doing.

I also reject the attempt by critics of so-called sanctuary policies to move the goalposts in the middle of this argument and say that while it’s true that federal law still applies in these places, what the sanctuary declarations and laws really intend to do is to prohibit cooperation between the jurisdictions.

Hold up, I say. That inter-agency cooperation is not required. This is professional courtesy at best, and it’s usually applied at the discretion of the local police departments. If the argument is that sanctuary laws unfairly eliminate that discretion, that’s fine. But that opens up a new question about whether, in the past, that cooperation has gone too far and the relationship had become incestuous, to the detriment of both immigrant communities and local enforcement. I think it had, and that it needed some correction.

Ultimately, I reject the idea that there needs to be any cooperation at all. It wrecks community relations, I insist. Let everyone do their own job, without expecting for someone else to do it for them. Everyone should stay in their own lane, I say, or there are going to be pile-ups.

What surprises me is that I get pushback from some of the local officers. Some seem gung-ho to round up illegal immigrants. Not all of them. In a roomful of about 20, maybe four or five fire back at me. The critics tend to be young. Old-timers like my dad tend to have a broader perspective on the issue, and they resent being deputized by federal law enforcement agents. But the youngsters don’t mind pitching in.

Maybe they watch Fox News and think the country is being “invaded,” so they want to do their part to hold the line. Or maybe they think they swore an oath to enforce all laws—local, state, and federal—and they intend to do just that. Or maybe they’re just flattered that a group of G-Men from Washington want their help in doing police work.

Whatever motivates them, these cops insist that SB 54 has been terrible for law enforcement agencies in California, and that it does indeed offer “sanctuary” to illegal immigrants. They claim their “hands are tied” and “criminals” go free because undocumented immigrants might be let out of the jail after serving time on a state violation before ICE agents can scoop them up. For them, sanctuary isn’t a myth. It’s real, and it’s dangerous.

The most compelling argument they make involves their commitment to keeping their community safe. If there is a bad guy in their city or town— who shouldn’t even be in the country because he’s here illegally—and he’s dealing drugs or driving drunk or robbing gas stations, then it’s their job to rid the community of that menace in order to protect the folks who live there. And if that means cooperating with ICE, then so be it.

I hear that. It’s a good argument. But it’s also flawed. After all, if this bad actor is as bad as they say, then he’s going to commit crimes that get him arrested and earn him a long stretch in state prison. That’s where he belongs. And how do you put him there? Often, it’s with the testimony of victims or witnesses. But if these victims and witnesses thought a police officer was a surrogate for federal immigration agents, they’d probably be afraid to talk to him. The bad guy would get away.

And who knows this simple fact better than anyone else? Not lawyers and politicians. But cops. Real cops, who know that oftentimes the most valuable weapons they have at their disposal are restraint and common sense.