Clinton spoke Wednesday night during the Civil Rights Summit at the Lyndon B. Johnson Presidential Library at the University of Texas in Austin. The library is hosting the three-day event to mark the anniversary of the landmark 1964 law that banned widespread discrimination against racial and ethnic minorities and women.
President Barack Obama is scheduled to give the keynote address Thursday and former President George. W. Bush will wrap up the summit later that day.
Clinton, the 42nd president, praised Johnson for pushing through laws that helped remove political and economic barriers for millions. He noted that Johnson was a "son of the South" and a "a Texan bred with the state's outsized ambitions (who) saw limitless possibilities in the lives of other people like him, who just happened to have a different color skin."
He also praised those who gave their lives in the civil rights struggle, such as Martin Luther King, Medgar Evers and other victims of bombings and shootings.
Clinton spent much of his speech addressing last year's U.S. Supreme Court ruling that struck down key provisions of the 1965 Voting Rights Act, which was also signed into law by Johnson. The ruling allows several states with a history of discriminatory voting laws, mostly in the south, to change election laws without federal approval.
Clinton noted laws in at least 10 states that require voters to present photo identification to cast ballots.
"We all know what this is about. This is a way of restricting a franchise after 50 years of expanding it," Clinton said. "Is this was Martin Luther King gave his life for?"
Supporters of the measures, mostly Republican conservatives, contend that the ID checks protect against fraudulent voting and thus help build trust in government. Critics see them as a way of discouraging the kind of voters who lack picture IDs and might be more likely to support Democrats.
Democrats have put voting rights among the top agenda items this year. Earlier this week,the Democratic National Committee (DNC) announced that Vice President Joe Biden is taking the lead on their Voter Expansion Project, which aims to promote voter registration, participation, and accurate vote counts for all registered voters.
"I've got to tell you, if someone had said to me 10 years ago that I'd have to make a pitch for protecting voting rights today, I would have said 'you got to be kidding," Biden says in a video they released.
A bipartisan group of lawmakers have introduced legislation to restore the part of the Voting Rights Act that was gutted by the Supreme Court, but it has not gone anywhere in Congress.
Clinton didn't address one of the hottest topics in the modern civil rights discussion - gay marriage - or touch on equal pay for women legislation that has broiled into an election-year issue in Washington and Texas.
Clinton signed the federal Defense of Marriage Act in 1996, which barred federal recognition of same-sex marriages. By 2013, Clinton said he believed the bill to be unconstitutional, arguing that it allowed discrimination. The Supreme Court ruled last year that the law improperly deprived gay couples of due process.
The Supreme Court ruling came at a time when polls showed a majority of Americans now support gay marriage. Lower court judges have repeatedly cited the Supreme Court when striking down same-sex marriage bans in several states. Gay marriage is now legal in 17 states and the District of Columbia.