BRIGHTON — Cali’s wagging tail showed she was a happy dog as she perused the classrooms at Pemayetv Emahakv Charter School. The 10-year-old chocolate Labrador retriever and her trainer, Seminole Police Department Officer Jack Morgan, came to school to sniff out any contraband drugs Oct. 18. None were found, but Cali was still rewarded with an empty water bottle to play with after searching middle school rooms.

Trained detection canines were introduced into public schools in Texas in the 1980s and the concept soon caught on around the country. Courts have upheld schools’ right to invite drug-sniffing dogs onto their campuses as a way to deter drug use and maintain a drug-free environment.

Although the fourth amendment of the U.S. Constitution prohibits unreasonable search and seizure, federal courts have upheld the constitutionality of random searches at public schools based on the fact that students do not have a reasonable expectation of privacy in school.

The drug policy is clearly explained to students at the start of each school year. Consequences are stiff; students receive a nine-day suspension and must spend 45 days in an alternative school located in their home counties. There used to be an alternative school on the Brighton Reservation, but it was cut for budgetary reasons.

The PECS drug prevention program has been in place for five years. Students never know when Cali and Morgan will appear, but the visits are done with regularity during the school year.

“They come at least monthly for surprise visits and never at the same time of day,” said PECS Principal Brian Greseth. “We’re trying to keep drugs off our campus. Students never know when the dog will be here, so hopefully they know not to bring drugs on campus.”

Dogs have up to 300 million olfactory receptors in their noses and can detect odors in parts per trillion; humans have about six million. According to dog cognition researcher Alexandra Horowitz, people might notice if a cup of coffee has a teaspoon of sugar in it but dogs can detect a teaspoon of sugar in a million gallons of water.

By inviting Cali onto campus, PECS put her snout to good use.

Greseth entered classrooms and asked each teacher to take the students outside for a few minutes. Morgan and Cali then entered and Cali went to work sniffing every backpack in the room. In one room, SPD planted a backpack with a magnet that had been wrapped in a towel with some marijuana.

To the human nose, the magnet smelled like any other. But to the superior canine olfactory system, the magnet was clearly contraband. Cali sniffed the bag and then sat at attention until Morgan congratulated her with praise. She was tested in this way twice while searching the classrooms and passed each time.

PECS’ history with drugs is a small one. Five years ago, marijuana was found once and four years ago it was found twice. It hasn’t been found since, which is the result Greseth wants to have every time Cali comes to visit.