The Family and Medical Leave Act (FMLA) is designed to provide temporary job-protected leave for workers who are dealing with serious life events, such as the birth or adoption of a child, the illness of a family member, or their own significant health problem. But does the law apply to afternoons of bass fishing? Probably not.

Travis Loyd, a top state employee and fishing enthusiast at the Illinois Department of Natural Resources, resigned from his job in February when it was revealed he had been using FMLA sick leave time to participate in professional bass fishing competitions all over the U.S. Loyd insisted he was under doctor’s orders to go fishing as a form of stress reduction.

In Loyd’s case, the state government didn’t catch the problem until outside organizations and news outlets reported it. However, there are ways companies can root out FMLA violators, including by hiring private investigators to look into the whereabouts of the employee in question.

Dana Connell, a shareholder at Littler Mendelson, told that companies don’t necessarily take advantage of this option, which has been upheld in court, as much as they could. “I think some portion of them just wouldn’t do surveillance, and another portion don’t recognize that it’s an option,” he said. As long as the investigator follows certain ground rules, explained Connell, there is no reason they cannot be used, successfully and within the bounds of the law, to bust FMLA cheats.

When there’s a great deal of suspicion around an employee’s FMLA time and an investigator is called in, Connell recommends getting human resources and senior management in on it. He believes in applying the same care in choosing and contracting a private investigator as the company would when retaining any other third-party vendor.

A company’s FMLA Philip Marlowe is limited in the ways he or she can conduct an investigation. The evidence gathering, according to Connell, will in most cases not include audio, because investigators recording audio might run afoul of eavesdropping laws. However, collecting video evidence in public areas is completely legal. “It’s certainly lawful to videotape them mowing their front lawn, but you wouldn’t want to take some sort of sophisticated video of their home,” he said.

This might sound limiting, but Connell said he’s learned from his work with clients that there’s an awful lot investigators can find out by standing on the street outside an employee’s home. He’s seen situations where employees will say they are on FMLA leave because they are too sick or injured to walk down the stairs or drive. They are then caught on video by investigators walking out of their house or apartment, lifting heavy objects into the trunk and driving away. “The video is sometimes just amazing,” Connell said.

When it comes an employee taking care of a sick relative or an infant, it can be trickier for both investigators and in-house lawyers to come up with clear answers. Connell pointed to a recent case in the U.S. Seventh Circuit Court of Appeals, which upheld the legality of FMLA leave for a woman who brought her terminally ill mother on a charity-funded vacation to Las Vegas. The court reasoned that since the woman was still caring for her mom on the trip, it was a viable use of leave.

So what’s a company to do after it finds out an employee has been abusing FMLA time? While it might be tempting to fire an employee before his fishing trip ends, Connell noted that dropping a worker midleave may lead to an FMLA interference charge against the company. “You might want to weigh what are the benefits and the risks of waiting until the end of that leave to bring them in and have the conversation,” he said.