For nearly 50 years, the Voting Rights Act of 1965 has served as one of the government's most effective tools for rooting out discrimination against minority voters. Wednesday, the Supreme Court will consider whether the law's methods are still constitutional.

The court will hear arguments in the case of Shelby County v. Holder, which calls into question one of the law's key provisions: Section 5. That section of the Voting Rights Act requires states with a history of racial discrimination to have any changes to their voting laws pre-approved by the Justice Department's civil rights division or the D.C. federal court.

There's no question voting rights have improved dramatically since the law was passed -- gone are the days of literacy tests and poll taxes, designed to keep minority voters from the polls. Given the significant improvements, Alabama's Shelby County argues that the Section 5 "pre-clearance" requirement "exacts a heavy, unprecedented" cost on the rights that states and local jurisdictions have to craft their own laws. Nine states are required to get pre-clearance under Section 5, as are certain jurisdictions in seven other states.

As recently as 2009, the Supreme Court expressed its skepticism of the continued need for Section 5. That year, when the court considered one Texas jurisdiction's right to "bail out" of Section 5 pre-clearance, Chief Justice John Roberts wrote for the majority that "these federalism costs have caused Members of this Court to express serious misgivings about the constitutionality of [Section 5]."

Since then, however, the landscape of voting laws nationwide has changed dramatically. Defenders of Section 5 argue the dozens of controversial measures, such as voter ID laws, passed in states across the country prove Section 5's continued relevancy. Furthermore, its proponents argue, striking down Section 5 would violate the deference the court should show to the legislative branch -- Congress renewed the Voting Rights Act in 2006, with overwhelming support from both parties, for another 25 years.

"The 15th Amendment to the Constitution makes quite clear this is in the province of Congress," Myrna Perez, a voting rights expert with the Brennan Center for Justice, a nonpartisan institute at the NYU School of Law, told CBSNews.com. "Given the clarity of constitutional authority, I think ultimately the court is going to be deferential."

If the court strikes Section 5 down, she said, "I think it would be an extraordinary interference with a constitutionally determined province of Congress."

Who to watch

To determine which way the court leans today, most interested parties will keep a close eye on Justice Anthony Kennedy.

"He's a justice who's expressed considerable concern about the use of race in public policy making in general, and yet he's somebody who also understands the Voting Rights Act and its significance fairly deeply," New York University School of Law Professor Richard Pildes, editor of "The Future of the Voting Rights Act," explained to CBSNews.com.

Constitutional experts like Elizabeth Wydra, chief counsel of the Constitutional Accountability Center, will also be watching Roberts. The Constitutional Accountability Center filed an amicus brief in Shelby v. Holder in defense of Section 5.