The U.S. Constitution is supposed to protect everyone from unlawful searches. It’s also supposed to guarantee equal protection under law.

But that’s not what happened last month outside the Goodwill Store in Bangor. Border Patrol agents pounced on a family there, questioned them and submitted them to fingerprinting and biometric records checks.

Why? Because they had brown skin and were heard speaking Spanish in public.

How do we know what the agents were thinking? They said so, in an affidavit filed in U.S. District Court in Bangor.

“While conducting patrol activities between transportation hubs (U.S. Border Patrol Agents Sean McDonough and Lewis Chambers) observed a group of people who appeared to be of Central American origin,” wrote Agent Matthew McLellan. “The (agents) entered the store where BPA McDonough overheard several people speaking in Spanish.”

The group was stopped on leaving the store and questioned by the agents. The agents called the initial interrogation voluntary, but once one member of the group told the agents that he was not legally present in the United States, they were taken into custody.

The ACLU of Maine called that “textbook racial profiling,” and they are right. The fact that well-trained federal agents believe that they have the right to stop and question anyone they want based on that person’s appearance should be of concern to everyone who cares about civil liberties.

The incident raises another troubling question. What were Border Patrol Agents are doing in Bangor, many miles from an international boundary? The answer is that the agency asserts that it has the authority to stop and question people within 100 miles of a border or coastline, so the entire state is Maine is under their jurisdiction.

Some will, no doubt, make much of the fact that a member of the group had a history of immigration violations and had been previously deported on two occasions. But that’s no justification for a search based on such a flimsy pretext.

The only reason we know about this case is that he was arrested. Otherwise, there would have been no reason to file the affidavit.

We have no records of how many other people were given the same humiliating treatment but ultimately were allowed to go on their way because they weren’t charged. The government could probably solve a lot of crimes if it required mandatory fingerprinting and DNA testing for every person on U.S. soil, but it does not because our Constitution does not allow it.

The Border Patrol is getting more aggressive in Maine, straying far from the border and looking for more than immigration violations. Agents stopped and questioned travelers in Brunswick last week, because of  what they called a “growing threat” to public safety.

In a statement, an agency representative said: “Transportation hubs are used by alien smuggling and drug trafficking organizations to move people, narcotics and contraband to interior destinations throughout the country.”

Combine that broad sense of mission with the agency’s view that its jurisdiction covers the entire state and you can see we have a problem. Add to the equation the agency’s view that skin color and native language are probable cause for questioning, and the problem gets worse.

We have been concerned about the “show your papers” policing that has been creeping into Maine. Before this gets any more intrusive, Congress and the courts should stand up for the constitutional rights of every person, citizen or not, and put an end to racial profiling.