WASHINGTON — The Supreme Court agreed Tuesday to go beyond its controversial Citizens United decision and consider striking down the limit on the total amount that wealthy persons may give to candidates and political parties.

The justices voted to hear an appeal from an Alabama donor and the Republican National Committee, which contends the total contribution limit of $123,200 per election cycle is "unconstitutionally low."

The case, to be heard in the fall, will focus on a little-known part of the campaign finance laws that set a total limit on contributions by individuals. Under these laws, individuals may give no more than $123,200 for each two-year election cycle. This includes a $2,500 limit for a federal candidate running for office and up to $30,800 per year to the political committees established by the national parties.

If the court were to strike down the limit, wealthy persons could write a single check for more than $1 million a year, which a political party could spread among several hundred candidates who were running for the House and Senate, said Fred Wertheimer, president of Democracy 21 and longtime advocate of the campaign finance laws.

Last year, a three-judge court in Washington upheld the limits on the grounds that the Supreme Court has consistently said that contributions to candidates can be restricted.

By contrast, the high court has said individuals may spend freely on their own for political ads and campaign messages. Three years ago, the court cited this free-spending rule in the Citizens United decision and ruled that corporate groups and unions may spend unlimited sums to back candidates.

That decision did not affect the limits on direct contributions to candidates and parties.

The new case, Shaun McCutcheon vs. FEC, is not an attack on the limits an individual may give to a single candidate. Instead, the court will decide whether Congress had a valid justification for limiting an individual's total contributions to candidates and parties.

Justices skeptical in patented seeds case

An Indiana farmer who clashed with Monsanto Co. over his replanting of its patented soybean seeds ran into steady skeptical questions Tuesday from the Supreme Court.

The justices strongly suggested that they would rule for Monsanto and decide that the company's patent protection for its genetically modified seeds covers not just the first planting, but also seeds that are generated later.

"Why in the world" would any company invest millions of dollars in creating a new seed if a farmer could buy one and freely reproduce it, asked Chief Justice John Roberts.

Mark Walters, a lawyer representing Indiana farmer Hugh Bowman, argued that a patent holder "exhausts" his rights after selling the product.

But the justices said that made no sense for products that are easily copied, or in the case of seeds, copy themselves.

Court sides with drug-sniffing dog

The Supreme Court on Tuesday sided with a drug-sniffing German shepherd named Aldo in ruling that police do not have to extensively document a dog's expertise to justify relying on the animal to search someone's vehicle.

The unanimous court overturned a decision by the Florida Supreme Court. That court had thrown out a 2006 search of a man's truck after Aldo "alerted" to the smell of drugs, saying police must compile detailed evidence of the dog's reliability before probable cause to search the vehicle is established. The police used the alert as probable cause to search the vehicle, and found the ingredients for making methamphetamine.

Information from the Washington Post was used in this report.