President Barack Obama used the 50th Anniversary of Martin Luther King Jr.’s “I Have a Dream” speech Wednesday to champion his administration’s latest legal efforts to stop voter discrimination and reform the nation’s criminal justice system.

Standing before the Lincoln Memorial, Obama told a crowd lining the National Mall that it takes constant vigilance to secure the gains the country has made since King delivered his famous speech from the same spot during the March on Washington in 1963.

“Whether by challenging those who erect new barriers to the vote, or ensuring the scales of justice work equally for all and the justice system is not just a pipeline from underfunded schools to overcrowded jails,” Obama said, “it requires vigilance.”

The U.S. Department of Justice and Attorney General Eric Holder Jr. have been pressing on those two fronts during the past month, with Holder hitting some of the same notes that Obama did on Wednesday.

The Justice Department has filed lawsuits against Texas over its voter-ID law and redistricting legislation, in the first major enforcement effort following the U.S. Supreme Court decision in June gutting a key Voting Rights Act of 1965 provision that required the state to secure federal permission for any voting law changes.

And Holder, the first African-American attorney general, decried what he called the “school-to-prison pipeline” when announcing sweeping new sentencing policies and advocated for an end to mandatory minimum sentences in some drug crimes.

On Wednesday, Obama adopted a sermon-like tone, but turned political when it came to voting rights. “We will win these fights,” he said. “This country has changed too much. People of good will regardless of party are too plentiful for those with ill will to change history’s currents.”

Former President Bill Clinton, speaking before Obama, also touched on the subject of the Supreme Court’s 5-4 ruling in Shelby County v. Holder, which struck down Section 4 of the Voting Rights Act, containing the formula for determining which jurisdictions must secure preclearance from the Justice Department or a federal court.

He said that advocates for voting restrictions have argued that the Voting Rights Act isn’t needed because some states “made it harder for African Americans and Hispanics and students and the elderly and the infirm and poor working folks to vote” in 2012 and “what do you know; they showed up, stood in line for hours and voted anyway.”

“But a great democracy does not make it harder to vote than to buy an assault weapon,” Clinton said. “We must open those stubborn gates.”

Contact Todd Ruger at truger@alm.com.