WASHINGTON — The U.S. Supreme Court heard oral arguments Tuesday in the case of Vernon Hugh Bowman v. Monsanto Company, et al. The case has obtained national attention because it seeks to determine the legal limits of patent infringement relating to genetically modified plants. This case involves “Roundup Ready” soybeans developed by Monsanto to be resistant to its popular herbicide.

Mr. Bowman, a 75-year-old Indiana farmer, evaded the licensing agreement on this type of bioengineered soybean, which requires farmers to buy fresh seed from Monsanto each time they want to plant Roundup Ready soybeans. Saving such seeds is illegal under patent law. Mr. Bowman obtained random seeds from a local grain elevator that he assumed had a strong likelihood of being Roundup Ready because the trait has become so widespread. He planted the seeds in a second crop. Monsanto argued that Mr. Bowman had committed patent infringement while Mr. Bowman’s attorneys argued that the patent was exhausted after the first use by a farmer of the bioengineered seeds.

After Chief Justice John Roberts opened by asking why any company would spend money on research to create a seed that would only become widely available and replicated without any remuneration for the company, the Supreme Court justices spent a large amount of time trying to discern exactly when patent infringement would occur in the case of Roundup Ready soybeans.

They appeared to agree that potential patent infringement would occur after the second generation of the seed, when a new crop was harvested and those seeds with the protective characteristic could either be saved or replanted.

Justice Breyer noted, “Infringement lies in the fact that (the farmer) has made generation three. It has nothing to do with generation two. That is just a coincidence. ..You know, there are certain things that the law prohibits. What it prohibits here is making a copy of the patented invention.”

The novelty of the technology involved in the case received a great deal of discussion. Mark P. Walters, attorney for Mr. Bowman, noted “This is obviously a brand-new case we’re dealing with — the doctrine of patent exhaustion in the context of self-replicating technologies.”

The Supreme Court has issued a full, public transcript of the oral arguments. A lawyer involved in the case said the parties expect a decision from the high court by the end of June.