(CBS News) NEW YORK - When he signed the federal Voting Rights Act on August 6, 1965, President Lyndon Johnson did not rely on understatement to express the significance of the legislation.
"Today is a triumph for freedom as huge as any victory that ever been won a on any battlefield," Johnson told members of Congress and dignitaries assembled in the Capitol's rotunda.
Standing beneath a large painting of the British surrender to George Washington at the Revolutionary War battle of Yorktown, and flanked by a statue of Abraham Lincoln, Johnson harkened back 350 years to the arrival of the first African-Americans at colonial Jamestown, Virginia, "in darkness and chains" as slaves.
"Today, we strike away the last major shackle of those fierce and ancient bonds," Johnson said. "Millions of Americans are denied the right to vote because of their color. This law will ensure them the right to vote."
The Voting Rights Act, along with the Civil Rights Act of 1964, proved to be the legislative pillars of the civil rights movement. They were pushed through Congress by Johnson after years of civil rights protests punctuated by the 1955 Montgomery, Alabama, bus boycott led by Rev. Martin Luther King to King's March on Washington in 1963. There were smaller legislative achievements along the way, such as the a limited voting rights bill Johnson shepherded through Congress as Senate Majority Leader in 1957.
By the time the Voting Rights Act passed, it had been a century since the Civil War and three post-war Constitutional amendments which outlawed slavery, extending the right to vote to former slaves, barred racial discrimination in voting laws, and granted equal protection to all citizens under the law,
It was President Ulysses S. Grant, the leading general of the Union Army, who signed the 15th Amendment guaranteeing African-Americans the right to vote in 1870.
But in some parts of the country, particularly in the South, legal segregation lived on, where states had imposed barriers, like poll taxes and literacy tests, that deprived most black Americans the opportunity to register to vote or cast a ballot.
The Voting Rights Act gave the federal government greater powers to prevent racial discrimination. For the past 48 years, the Justice Department has routinely monitored elections and reviewed changes to any voting rules, ranging from poll locations and hours, to registration and identification requirements and the redrawing of legislative district lines.
The issue before the Supreme Court in next Wednesday's oral arguments in "Shelby County v. Holder" is just one part of the Voting Rights Act -- Section 5 -- which requires 9 states and parts of 7 others to obtain Justice Department approval, known as "preclearance," before changing voting laws or maps.
Some of the states covered in full by the Act, like Alabama, where the plaintiff's case originated, contend that Section 5 is an outdated burden, because racial discrimination is "scattered and limited."
"It's not the same as it was as 1964, and to use a test from 1964 is way out of date," Shelby County Attorney Frank Ellis told CBS News Affiliate WIAT/Birmingham. "It's time for it to be set aside."
The act's defenders believe the law is as relevant as ever and look no further than last year's election, when states such as Florida and Ohio shortened the days and times for the ever popular early voting.
Proponents also point to a surge in states passing laws requiring voters to produce a government-issued photo ID in order to exercise their right to vote.
Four southern states covered by the Voting Rights Act - Alabama, Mississippi, South Carolina, and Texas -- and one northern one, New Hampshire -- were among 10 states to adopt strict photo voter ID laws in the past two years. Earlier, Georgia and Louisiana did so.
The Virginia legislature passedlast week, but Gov. Bob McDonnell has not indicated how he will handle it. McDonnell, a Republican bucking the trend in Republican-led states, supported a voter ID that loosened the requirements in Virginia last year.
Detractors say photo voter ID laws are present an unfair burden on poor, minority, and youthful voters, who are the groups most likely to lack a driver's license or the means to obtain the documents, such as birth certificates, required to get an official ID.
U.S. Attorney General Eric Holder relied on Section 5 to challenge the recent photo voter ID laws in Texas, because the Justice Department found, it discriminated against Hispanics, and in South Carolina, where DOJ found the law discriminated against black voters. The government won its lawsuit to block the law in Texas, but lost against South Carolina. The Alabama and Mississippi laws are still undergoing preclearance review.
"The right to vote is not only the cornerstone of our system of governance, it is the lifeblood of our democracy," Holder told a crowd in Columbia, South Carolina, on Martin Luther King Day on January 16, 2012. "The arc of American history has bent toward the inclusion - not the exclusion - of more of our fellow citizens in the electoral process. We must ensure that this continues."
Dr. King's hand was one of the dozens shaken by President Johnson after he signed the Voting Rights Act in Washington 48 years ago.
That day, Johnson told his audience he would not be satisfied until every qualified person could exercise the right to vote "unquestioned and unrestrained" in "every precinct" of the country.
"The denial of the right to vote is still a deadly wrong," Johnson said.
Congress has endorsed that vision by re-authorizing and amending the Voting Rights Act four times by sizable majorities, most recently in 2006. Between 1982 and 2006, the Justice Department reported it used Section 5 a total of 2,400 times to block what it considered discriminatory voting law changes in the states.