A federal jury ruled Tuesday for R.J. Reynolds Tobacco Co. in a high-stakes dispute with Star Scientific Inc. (STSI) over Star's patent claim for a new method of curing tobacco in a way that reduces certain cancer-causing toxins.

Star was seeking several hundred million dollars from RJR, a unit of Reynolds American Inc. (RAI), alleging that the nation's second-largest tobacco company encouraged its farmers to practice Star's invention without permission.

But after a four-week trial, a jury in Baltimore sided with Reynolds, ruling that RJR did not infringe Star's patent and that the patent was invalid.

August Borschke, chief patent lawyer for R.J. Reynolds, said the company was pleased with the verdict.

The jury "saw what we have known all along, that Star's patents are invalid, and they should not have been issued in the first place," Borschke said. "The jury also confirmed R.J. Reynolds did not infringe Star's patents in any event."

A spokeswoman for Star couldn't immediately be reached for comment.

The jury verdict dealt a significant blow to Star's fortunes. Star's shares tumbled more than 80% in after-hours trading, to 77 cents.

The verdict is an important marker in the case but likely will not be the last word in the dispute. Star is expected to appeal the ruling.

-By Brent Kendall, Dow Jones Newswires; 202-862-9222; brent.kendall@dowjones.com