Calvin E. Murphy, a superior court judge, did not grant TSG’s wish. In a written order, Judge Murphy said, “Enforcement of the noncompete provision in the manner articulated” by TSG would effectively bar Mr. Bollinger “from seeking employment anywhere in North America in the only profession he has practiced since graduating high school.”

TSG appealed, however, and the North Carolina Court of Appeals reversed the decision. A little after that, Mr. Harris, American’s chief executive, called Mr. Bollinger at home and told him not to return to work.

“My heart was broken,” Mr. Bollinger said.

About a year after the Appeals Court decision, TSG filed an amended complaint against Mr. Bollinger and others, alleging that he had quietly continued working for American even while the injunction was in place, and asking the court to prohibit him from working there ever again.

The new complaint cited evidence, like photos of Mr. Bollinger’s wife’s car parked at American’s facility, and a phone call TSG had received from “a female who would not reveal her identity,” who said Mr. Bollinger had continued to work there. At one point, TSG hired a private investigator to look into it.

“It is regretful that a great deal of money and resources have to be spent in our court system which could be otherwise spent on employee raises or investing in new equipment to make us more competitive,” Mr. Harris said in an emailed statement.

Perhaps more important, the whole ordeal had caused a “strain” between TSG and its customers. The complaint said that in 2015 one customer had said it planned to transfer its business to American; another had asked TSG to resolve the dispute in a way that allowed Mr. Bollinger to continue at his new job.

“When a competitor has the opportunity to poach that knowledge without making the investment in research and development, it gives them an unfair advantage, which a three-judge panel agreed happened in this case,” said Jack Rosenstein, TSG’s chief executive, in an emailed statement.