In Takoma Park, Md., high school junior Ben Miller, seen in 2013, was the first to register to vote at his school after the D.C. suburb lowered the voting age for municipal elections. (Bill O’Leary/The Washington Post)

The District has legalized marijuana. Its city council is poised to give new parents 16 weeks of paid leave. And before lawmakers seal the deal on that progressive plan, a trio of council members on Tuesday introduced another idea that could make waves nationally: letting 16-year-olds vote.

It’s not unheard of. Sixteen-year-olds have been allowed to vote in municipal elections for two years in Takoma Park, Md., a liberal suburb of the District. And in San Francisco, lawmakers are eyeing a voter referendum next year to decide on lowering the voting age for local and state elections.

But under the proposal in Washington, the nation’s capital would go further than any state or municipality by allowing 16- and 17-year-olds to vote in federal elections.

Council member Charles Allen (D-Ward 6), the chief author of the measure, contended Tuesday in introducing the legislation that there is nothing in the 26th Amendment that expressly forbids younger Americans from voting. The Constitution, he said, only ensures the right to vote of those who are 18 or older.

(For the record, the 26th Amendment reads: “The right of citizens of the United States, who are eighteen years of age or older, to vote shall not be denied or abridged by the United States or by any State on account of age.”)

“It is constitutional,” Nathaniel Persily, a professor of law at Stanford University, said of the D.C. proposal. “There is no right to vote in the Constitution . . . it doesn’t say you can disenfranchise people who are under 18 . . . the amendment prevents against discrimination, it doesn’t prevent against greater inclusion.”

That notion has a diverse group of advocates hoping for a sea change for civic involvement, which is notoriously lackluster in Washington, where residents are allowed to vote for president but have no voting representation in Congress. Last year, just 38 percent of registered voters turned out for the city’s mayoral election.

An early organizer for the youth voter initiative was Michelle Blackwell, 44, who said she was upset this summer to see city lawmakers barely listening to the District’s youths amid a spike in violence.

An acquaintance of Blackwell’s, Tenika Fontanelle, was one of the year’s homicide victims. “So that was what prompted me to find some way to give young people a voice,” she said. Blackwell decided to focus on politics. “They need some kind of responsibility for their own futures. I think getting them involved in politics is a great way to give them a stake.”

Allen said he was initially opposed to the idea but came around quickly, thinking about all of the rights and responsibilities that are already given to 16-year-olds, including driving, paying taxes and the potential to be charged as an adult in court.

“It’s an age when we remove, generally, the mantle of childhood and instead apply many expectations of adulthood,” Allen said. “We give them the burden of responsibility, but not the ability to have a voice in society.”

And Allen says starting a good civic habit is another motivation: “You have to vote a couple times before it becomes a habit, and the earlier we have them in that routine the better.”

Council members David Grosso (I-At Large) and Brianne K. Nadeau (D-Ward 1) co-introduced the legislation.

“The most common retort I’ve heard back is ‘Really? You think a 16-year-old can make an informed decision?’ ” Allen said. “To me, the answer is, ‘Yes.’ ”

If the measure gains steam in the D.C. Council, it could set the District on course for another conflict with conservatives in Congress, who routinely work to thwart the District’s most liberal policies through oversight of its budget.

Persily said the legal argument against allowing younger residents to vote could be tenuous. Opponents, he said, would have to show that allowing younger residents would dilute the voting power of older residents. “That could be difficult,” he said.

Abigail Hauslohner contributed to this report.