CHICAGO – Jeffrey Allen would answer his work BlackBerry during Thanksgiving dinner, during his son's soccer match, on any number of Saturday afternoons.

The phone would buzz with work-related texts, e-mails and calls from the time he woke until he headed to bed — and, with it always in reach, he would respond.

"I just saw it as part of the job," said Allen, 51, a Chicago police sergeant.

But it was not a part of the job he was paid for, Allen alleges in a class-action lawsuit against the city of Chicago filed five years ago that heads to trial this month. He and about 50 officers who have joined the suit seek overtime pay for off-duty hours spent monitoring and responding to work e-mails and phone calls on their company-issued mobile devices.

Anyone familiar with the ping of a late-night e-mail, a weekend call from a boss or a mid-dinner glance at a text message has felt the inescapability of work in the age of smartphones. But while constant connectedness has become the norm, it has also become a source of overtime litigation — and attorneys say that could increase under a proposal from the Obama administration to make millions more salaried Americans eligible for overtime, including many in managerial positions.

"As managers, they are more likely to be checking in during off hours," said Phillip Schreiber, a Chicago-based employment lawyer at Holland & Knight who represents businesses and is not involved in the police suit.

The new overtime rule proposed by the Labor Department last month would raise to $50,440 the minimum salary an employee must make before he or she can be classified as exempt from overtime, which would be up from $23,660. The government estimates that would extend overtime pay to nearly 5 million salaried workers in a range of professions, from store managers to staff accountants, who currently are exempt under "white collar" provisions. The salary threshold doesn't affect certain workers, including teachers, outside sales representatives and certain hourly computer professionals.

More overtime-eligible workers means greater risk of litigation and greater need for employers to establish clear policies mandating that such employees not field work-related communication on their mobile devices when they're off the clock, unless they're authorized by a supervisor, Schreiber said.

"In addition to having a policy, you have to have training," Schreiber said. "And you don't penalize employees who don't respond to e-mails or texts off hours, because they're not supposed to."

In response to overtime concerns, the Labor Department plans to seek public comment on the use of smartphones to work during off hours and could subsequently propose a new rule or guidance on the topic.

Allen's case could be a cautionary tale for employers. Allen felt he had found his calling when he was assigned to supervise a money laundering team in the Chicago Police Department's Bureau of Organized Crime. He didn't mind the extra hours he put in on his company-issued BlackBerry because it was a prestigious post with opportunity for promotion, and he was driven to succeed, he said.

An hourly employee, he was eligible for overtime but never filed for it in relation to BlackBerry use, as it was implicitly understood in the unit that that wasn't done, he said.

But when Allen was transferred from the bureau to a district job with lesser status, the payoff of prestige and potential career advancement that motivated him to be available at all times evaporated, he said. His attorneys have calculated, based on his phone records, that during one 28-day period he spent 720 minutes, or 12 hours, on his BlackBerry on off-duty work-related phone calls. That doesn't include reading and responding to e-mails.

"I could not have done the seizures or the work I did without the BlackBerry," said Allen, who is now a tactical sergeant. "But I need to be compensated now for the time that I put in, because the consideration that I was intending them to give me was taken away from me."

The city's law department said it is inappropriate for them to comment on the specifics of active litigation. But in general, "the city believes this suit is without merit and that the Chicago Police Department has an established and utilized process for officers to request and receive overtime compensation," spokesman John Holden said.

The police department had no written policy on off-duty BlackBerry use when the lawsuit was filed in May 2010, Geiger said, but it published one a few months later that stated employees were not obligated to carry their devices or respond to them while off-duty. An updated policy issued in 2013 states employees are not to use their devices while off-duty at all unless a supervisor directs them to perform work immediately and authorizes overtime pay for it.

The lawsuit heads to a bench trial Aug. 17.

Because many such cases were settled, getting a judgment could mean Allen v. Chicago sets a precedent for overtime lawsuits related to smartphones, said Laura Bacon, a Chicago-based employment lawyer with Nixon Peabody focused on advising clients on commercial litigation and labor issues.

Bacon recommends companies get in front of the issue with written policies to which employees must consent, given the expense of defending against such suits.

In 2011, Volkswagen AG cut off corporate e-mail between 6:15 p.m. and 7 a.m. for 4,000 employees in Germany. Director of communications Carsten Krebs said it has been "a huge success."

"The employees are very happy with the new policy," Krebs said. "They can spend more time with their families, they like the new work-life balance."

But Kelly Goldsmith, assistant professor of marketing at Northwestern University's Kellogg School of Management, believes the solution lies not in technology but in a company's culture.

"If you really want to shut down the workaholics, you have to do it firm-wide by setting that example," she said.