After more than two years, Matt Lee won back $2,400 taken from him through civil forfeiture in July 2011 by the sheriff department in Humboldt County, Nev. (Gabe Silverman/The Washington Post)

AMERICANS LAST week got a public display of President Trump’s decision-making style. To call it “impulsive” gives him too much credit.

Mr. Trump met with a group of sheriffs, who, as they groused about their critics, seem to have extracted a new policy position from a credulous and apparently ill-informed president. The sheriffs spoke about “civil asset forfeiture” — a bizarre police power prone to abuse yet beloved by law enforcement — and Mr. Trump concluded that only “bad people” would pressure them to change the practice.

If that is so, there are a lot of “bad people” in the United States. An ideologically diverse, bipartisan movement that includes many Trump supporters opposes civil asset forfeiture, because it allows police to seize property from Americans on shockingly flimsy legal grounds.

Officers do not have to show that those deprived of their property ever committed a crime. Often, all they need to show is suspicion that cash or cars might have been related to criminal activity. In practice, officers have noted the presence of energy drinks and junk food in cars, a motorist’s facial twitches under questioning, the presence of duct tape, “inconsistent” statements from motorists who do not speak English well, and other hardly damning details to gin up the required “suspicion.” Under a state-federal program, police departments then get to keep a slice of the money they take. Owners of seized property can appeal, but it is on them to show that the goods were legally acquired, and it is expensive to lodge the necessary legal objections.

Investigations of civil asset forfeiture, which was conceived as a way to combat major international drug traffickers, has uncovered examples of unforgivable abuse. Lives have been upended. Take Ming Tong Liu, a Georgia man whose story The Post detailed in a 2014 investigation. He raised $75,000 in cash from relatives to buy a Chinese restaurant. Pulled over for going 10 miles per hour over the speed limit, the police took his $75,000. He only got it back after 10 months and a lot of hassle, at which point he could no longer buy the restaurant.

Mr. Trump did not seem to know any of this, appearing confused about what the program actually does. The sheriffs did not help. “They make up stories,” one sheriff said of civil forfeiture critics. No one at the table offered to speak up for those whom police have victimized, or to point out the clear conflict of interest in allowing police departments to profit from the assets they seize.

A variety of states have passed or are considering reforms to their civil forfeiture system. Some have abolished it, stipulating that assets can be seized only from convicted criminals. Others have simply specified that it can be used only in cases involving a large amount of cash. At the least, seized money should go into state and federal treasuries, not directly to police.

We can only hope that Mr. Trump or his advisers get the real story. If not, state governments should ignore him.