WASHINGTON — The U.S. Supreme Court has plans to take on a case involving the patent rights of Monsanto Co.’s “Roundup Ready” soybeans bioengineered to be immune to their widely used herbicide. Oral arguments will begin sometime in 2013.

“This will be a case that the bigger agricultural community will be watching closely,” said Dale Durchholz, senior commodity analyst with Agrivisor L.L.C. in Bloomington, Ill.

The case, Bowman v. Monsanto Co., involves a situation where an Indiana farmer, Vernon Hugh Bowman, initially planted bioengineered soybean seeds according to the parameters established by Monsanto, the manufacturer. But he then bought cheaper seeds from a grain elevator to plant a second crop that he hoped might also offer “Roundup Ready” protection.

That is because he knew that the less-expensive seeds had about a 90% chance of also being immune to the Roundup herbicide. The trait has spread through almost all U.S. soybean seeds, said Alan Wexelblat, a commentator with a blog devoted to copyright and other legal issues called “Copyfight.”

Mr. Bowman’s maneuver to save money and circumvent patent-related restrictions was illegal, in the opinion of Monsanto, and lower courts that ruled on the case agreed.

Mr. Bowman’s case, though, hinges on a concept known as patenting’s “exhaustion doctrine,” which asserts that it is possible to only sell a patented product once and keep the protection. Mr. Wexelblat said Mr. Bowman replanted generic seeds — not the ones from Monsanto that he had signed an agreement about — and therefore Mr. Bowman expected the exhaustion doctrine would apply. But Monsanto successfully argued in lower courts that seeds with the Roundup Ready gene in them, wherever they were obtained, constituted a patent infringement if they were planted to produce more soybeans without the knowledge of Monsanto.

The agricultural law community has assumed that the Supreme Court is interested in this case because it explores patent rights for agricultural biotechnology that may be replicated, such as seeds. Such considerations are likely to come up with greater and greater frequency as the universe of bioengineered food-related products expands.

As things stand now, it is settled law that saving bioengineered seeds is not allowed. That is because the individual who first plants the seeds does not actually buy them, but rather purchases a license from the patent holder allowing them to use the technology embedded in the seed, said A. Bryan Endres, an agricultural and consumer economist from the University of Illinois. He believes the Supreme Court, which rarely selects a case from the agriculture sector for its docket, may be interested in making a clearer determination on intellectual property protection for self-replicating patented products. Or, he argues, the court may believe intellectual property rights need to be scaled back in cases involving technology that can multiply itself.

Mr. Endres said that an Indiana federal trial court, as well as the Court of Appeals for the Federal Circuit in Washington, ruled in favor of Monsanto in 2011, making the argument that, even if patent rights in the seed are exhausted by sale to a grain elevator, once a second farmer plants the bioengineered seed and it develops, the farmer has recreated the patented Roundup Ready seed without permission of the owner of the patent.

Many questions remain about the scope of a patent on an agricultural product. One is the fact that patent protection does not last forever.

“An interesting twist on this case is what happens when the patent (on Roundup) runs out,” said Mr. Durchholz, which he said will occur relatively soon. He noted that Monsanto already has introduced a second generation of Roundup Ready soybeans, which he said have not yielded substantially more soybeans than fields planted with the first Roundup Ready seeds.

Monsanto has its protocol to ensure it receives a financial return and patent protection for the expenses involved in the creation of bioengineered soybean seeds. Farmers buy the seeds and sign an agreement they will not hold back seeds to plant a second crop. Monsanto requires them to buy new Roundup Ready soybeans for each crop in order to recoup the embedded extra costs that the company regards as fair payment for the patented research.

Michael Cordonnier, Ph.D., a soybean analyst, said Monsanto enforces its right to patent protection by randomly checking the planted soybeans in the field to see if they are the Roundup Ready variety.

“They can tell by just looking at the leaves,” he said. A check of their customer list can reveal if the farmer bought the designated seeds from Monsanto or obtained them some other way.

Dr. Cordonnier said he questions the validity of the case, while admitting he hasn’t followed it closely. To him, the issue is one of contracts made and contracts broken.

“The farmer signs an agreement that he is not going to replant soybean seeds without buying from Monsanto,” he said. “This farmer violated that contract.”