Attorney general and gubernatorial candidate Doug Gansler listens to reporters after his remarks during a Thursday news conference in Silver Spring. (Bill O'Leary/The Washington Post)

It’s one of the fault lines of modern parenting: What do you do when you stumble into a teenage drinking party? Look the other way? Shut it down? Call the police?

Susan Burkinshaw, a PTA mom from Germantown, Md., admits that she would want to close her eyes, plug her ears and back right out the door. “I think that’s what we would all want to do, but that doesn’t mean it’s the right thing to do,” she says, urging parental courage.

What is very often a private conversation behind closed doors between parent and erring adolescent became fodder for broader debate this week as the public parsed the most recent controversy surrounding Maryland Attorney General Douglas F. Gansler (D).

In a vivid photograph published Thursday, Gansler is shown walking through a throng of teen revelers at a party held at a rented beach house where his son was the DJ. Three teens are dancing on a table. At least one red plastic cup is in view. Gansler said at a news conference that the red cups at the party might have contained Kool-Aid but probably contained beer.

Gansler has acknowledged that he did nothing to stop the apparent underage drinking at the house.

Maryland Attorney General Doug Gansler, in the white shirt at upper center, is seen at a high school graduation party that his son was attending in June at a beach house in Delaware. (ABC News)

A month into a campaign for governor, Gansler — Maryland’s top law enforcement officer — has described his inaction as a mistake. But he also invoked the conflicts of parenthood: “How much do you let them go? How much do you rein them in?” He said he was “no different from any other parent.”

Some parents understand his conundrum, having grown up in the 1970s and 1980s and recalling all too clearly their experiences with teen parties. They turned out all right, the thinking goes. And how wrong can it be to look past some transgressions, especially just months before kids head off to college?

All parents don’t see it the same way.

“I would have ended the party,” said Deidra Speight, a mother of four in Upper Marlboro, Md. “Absolutely. Just think: If something would have happened, it could have been horrible. I don’t think he was thinking of that.”

Added Speight: “I always feel like parents are responsible. Period. End of story. As soon as you figure it out, you need to fix it.”

Not every parent navigates the experimentation of the teen years the same way. Some parents say kids need rules that don’t bend. Others say many high schoolers are going to drink anyway and might as well do it with the benefit of parental supervision. Still others don’t think that their teens would try something illegal.

Gansler’s moment of decision in South Bethany, Del., came June 13 at a party after his son had just graduated from the Landon School in Bethesda. Locally, many seniors cut loose after graduation with trips to Maryland and Delaware shore towns for “Beach Week.”

Takoma Park parent Jeffrey Hopkins, whose daughter went to Beach Week in 2012, said many parents are torn about the celebration. “You want to give them freedom,” he said. “You want to reward them for a successful graduation from high school. But at the same time, you realize there’s real risk there.”

Hopkins said he has asked himself what he would have done in Gansler’s situation and admits that it’s hard to be sure. Judging by the photo, he said, he would not necessarily conclude that there was drinking.

But if he knew of underage drinking, he would intervene.

“We don’t live our lives by black and white laws,” he said. “It mostly relies on the kind of judgment you can make at the time.”

At first, Gansler had told the Baltimore Sun, which first reported the story, that even if there was widespread drinking at the party, its relevance was questionable. “The question is, do I have any moral authority over other people’s children at Beach Week in another state?” he was quoted saying. “I say no.”

Gansler has since softened his response and said neither he nor his son drank at the party.

But some parents still take exception. They say if they had walked into an underage beach party, they could not simply walk away. They would have summoned help or taken action.

They would feel responsible.

Michelle Jackson, who has a child at Eleanor Roosevelt High School in Greenbelt, said she would talk to chaperons first, but if they seemed unconcerned, “I’d call the police.”

“I can’t imagine condoning a party where there is underage drinking,” she said.

The Beach Week tradition is deeply rooted at many of the region’s schools. Groups of friends rent a house together. Some parents supervise; some don’t. Many parents ask students to sign contracts banning certain behaviors and outlining expectations.

Longtime activists on underage drinking, such as Trina Leonard, a parent of two students at Walter Johnson High School in Bethesda, say that many make the mistake of believing that as long as teens are not driving, it’s all right if they drink.

But she points out other dangers: alcohol poisoning, unintended sex, assaults, legal trouble, long-term dependence.

If she were at the party, she said, “I’d go over and be sniffing what is in those cups” to determine what was going on.

Leonard said she has already told her teenagers: There will be no Beach Week unless she goes with them.

In Potomac, Md., Meredith Geisler, a mother of two, said she has empathy for Gansler, whose decision-making was the talk of a radio show she listened to on Friday.

Geisler said her daughter went to Beach Week with a group that included families she’d known for years and chaperons who stayed nearby and did drop-in visits. She believes that there was never a party in their house.

“You have to walk that fine line of letting them grow up, giving them some space,” she said, “but having it controlled.”

Burkinshaw, the mom from Germantown and co-chair of the health and safety committee of the countywide PTA, said that in a perfect world, a parent would ask partygoers how old they are and what they are drinking — and end the festivities if laws were being broken.

“I know parents struggle with this, and I know a lot of people do what Doug Gansler did,” she said. “It’s a societal issue . . . and it means we have to make tough choices and be strong parents.”