CONCORD — It may be 225 years old but the U.S. Constitution is still a very relevant document, retired Supreme Court justice David Souter told more than 1,300 people Friday night at the Capitol Center for the Arts.

But Souter warned that democracy is in danger when two-thirds of Americans don't even know there are three branches of government.

Souter, of Hopkinton, spoke Friday at the launch of Constitutionally Speaking, a collaborative civic engagement initiative of the New Hampshire Supreme Court Society, the New Hampshire Humanities Council, the UNH School of Law and the newly formed New Hampshire Institute for Civic Education.

Today is Constitution Day and it is also Souter's 73rd birthday. It was Sept. 17, 1787, when the Constitution was adopted by the Constitutional Convention.

Souter called civic ignorance “a public problem and a public responsibility which is second to none.”

“It didn't used to be this bad,” when he was a student at Concord High School in the 1950s.

“The good news is there are a lot of terrific civics teacher in New Hampshire who are trying to turn that around. One of the problem is they don't have the materials,” he said, nor the time when laws like No Child Left Behind limit such offerings.

Souter said he does not worry about a military coup or another financial meltdown as much as fear that people will not know who is responsible.

“Someone will come forward and say give me power,” to solve the problems. Souter said that is how Rome fell.

Margaret Warner, senior correspondent and anchor of PBS NewsHour sat with Souter on the stage. Warner began her career as a newspaper reporter in New Hampshire and knew Souter from her years in the Granite State.

Souter is working to advance two major initiatives: to reform civics education in New Hampshire public schools so that when they graduate they will have the basic information needed to engage in civic dialogue; and to encourage civil and spirited discord.

The latter was the subject for the night.

The audience included public school students, teachers, administrators, scholars of law, professors, members of the state judiciary and engaged community leaders.

Warner said “everyone in this room really shares a conviction that the Constitution is essential to who we are today.”

Souter said the Constitution is both structural and has a great breadth of language related to liberty. The role of the courts is to figure out what makes sense, which changes over time.

Americans need to read the actual cases of the Supreme Court, Souter said, rather than the interpretations, to really understand why the courts act as they do.

He noted in the Kelo vs. New London case, in which Souter sided with the majority, held that the government can take land for eminent domain. A neighbor came up to Souter after there were protests at his New Hampshire home and told him that what was being said in the Boston papers was not what the decision stated.

Souter was asked by Warner why court's interpretation of the Constitution changed from Plessey vs. Ferguson, which held it was fair to offer equal but separate rail cars for blacks and whites, and Brown vs. the Board of Education, which struck down segregation 60 years later.

The big difference was the perspectives from experiences of the justices and what seemed fair.

“Those justices remembered slavery ... equal facilities in a railroad ... that looked like real progress,” Souter said. “We can only see what our experience has opened our eyes to.”

Souter declined to answer some questions related to recent decisions of the Supreme Court, including on Citizens United and the Affordable Care Act, because he is still presiding part-time on the First Circuit Court of Appeals. He retired from the high court in 2009.

He said his own experience as a Superior Court judge in New Hampshire gave him great respect for the jury system.

Asked by a Gilford High School student where he stood on the states and their abilities to nullify federal law, Souter said, “We fought a civil war about that. The nullification side lost,” and he does not see the supremacy clause changing.

In closing, Souter said he is not an optimist on the future of American democracy if we do not deal with the educational aspects of civics.

“We are still in the game but we have serious work to do,” he said.

WHAT's NEXT: The program was recorded and is available online today at constitutionallyspeakingnh.com.

ptracy@unionleader.com