PORTLAND — The safest place for teenagers to drink alcohol is at home under the supervision of a parent, some experts say. It’s an option that is perfectly legal under Maine law.

That is not what Barry and Paula Spencer, of Falmouth, are alleged to have done last Saturday. Police say they allowed a group of high school students to have a party at the couple’s Falmouth home. They are charged with furnishing a place for minors to drink alcohol.

According to police, some of the teenagers at the Fieldstone Drive party drank so much they vomited on cars in the driveway and one had passed out on a neighbor’s lawn. The group reportedly included members of Falmouth’s state championship baseball and boys’ lacrosse teams.

When it comes to alcohol and minors, the law respects parents’ religious practices and their personal beliefs about how they choose to raise their children, said Guy Cousins, director of the Office of Substance Abuse in the Maine Department of Health and Human Services. They may serve alcohol to their own children in their own home.

“When you involve a child outside of that,” he said, “that is over the line.”

The idea that parents should try to control teen drinking, rather than work to eliminate it, began to fade a couple of years ago, said Joanne Morrissey, the program director of Portland-based 21 Reasons, a group that works to reduce alcohol and drug use among teens.

“There’s been a huge pendulum shift in that regard,” Morrissey said. “Parents are now saying that they would do anything possible to prevent their kids from drinking.”

It’s working, Morrissey said, because rates of teen drinking have been falling for the past few years across the country.

Parents who try to control drinking at teen parties by hosting the events are well-intentioned, but the parties get out of hand quickly these days, said Frank Watson, who was charged with providing minors a place to consume alcohol four years ago after members of his son’s championship baseball team at Deering High School drank beer at a party at Watson’s house.

Watson spent eight days in jail, paid a fine of $3,000 and racked up $60,000 in legal bills because of his charges.

“With all the texting and Facebook, once one kid finds out about it, 50 know about it in an instant,” he said.

That’s exactly why parents shouldn’t believe they can control alcohol consumption just because they are hosting a party in their own home, said Ralph Blackman, president and chief executive officer of the Century Council, an alcohol industry-funded group that works to eliminate teen and binge drinking.

Those parents have “only controlled the environment; they didn’t control the drinking,” Blackman said after the Falmouth event was described to him.

Some parents believe they are doing the right thing by hosting a party and making sure none of the teenagers drive after drinking, but they are naive if they think they can control teenagers’ behavior, said Janet Mills, a former attorney general and district attorney.

“It’s not easy for a parent to be a police officer in their own home,” she said.

She said parents who host a party for teenagers where alcohol is served are taking big risks. They could be sentenced to jail, or they could be sued by another parent if someone gets hurt.

Not everyone agrees that a zero-tolerance policy is the best approach. Considering the exposure to drinking that teenagers face when they leave home and go to college, it makes sense to allow teenagers to experience their first taste of alcohol at home, said Edgar Allen Beem, a Yarmouth writer and former school committee member.

“The bottom line is that kids are going to drink, and you just can’t say ‘no,’ ” Beem said.

In 1999, Beem and another parent found out about an after-prom party that their teenagers were attending, he said. They stood watch at the party — which was held in a field, not any of their homes — to prevent any of the inebriated teenagers from driving.

Beem and the other parent faced no charges because they had not hosted or sanctioned the party, nor had they furnished the alcohol. He noted that the teenagers were going to drink whether he was there or not.

Still, he said, he can understand why parents might want their teenage son or daughter to drink at a party at home, if they are going to drink anyway.

“It’s a fine line to walk. You want to protect the kids,” he said. “I wouldn’t want kids to go off to college without ever having had a drink. Those are the kids who end up in a hospital.”

Rep. Mark Dion, D-Portland, a former Cumberland County sheriff, remembers when he was 14 or 15 years old, and it was decided he was old enough to have a sip of brandy with the men of the family. He also remembers that at age 17, during the summer before he went off to college, his father tossed him a can of beer as they sat together in a fishing boat.

There’s a big difference between that and hosting a party where the teenagers attending drink alcohol without their parents’ permission, he said.

“The opportunity for a father to share a beer with a son — that’s an internal family decision,” he said. “That is different than facilitating a group activity.”

By hosting a party where teenagers are provided alcohol, he said, an adult conveys the message that it’s necessary to drink in order to socialize. What’s worse, he said, it sends a disrespectful message about the teenagers’ parents.

“What you have done is subverted the role of the parent in that family,” he said.