This was the question posed by Lauren Weber of The Wall Street Journal in her article, "Can You Sue the Boss for Making You Answer Late-Night Email?"
The author cites Pew Research Center studies that report 44% of internet users regularly did some job tasks outside the workplace. While smartphone technology has greatly increased the availability of workers, it hasn’t necessarily increased their overtime. While the vast majority of white-collar workers are exempt from the Fair Labor Standards Act and Minimum Wage Act, new Department of Labor rules are expected to change this.
In Washington, what constitutes “work” is the often a major dispute in minimum wage and overtime cases. “Work” is not defined in the MWA or the FLSA, but the courts have defined work as activity or inactivity that is requested or allowed by the employer and that is pursued predominantly for the employer’s benefit, even though it confers a benefit on the employee.
See: Tennessee Coal, Iron & Railroad Co. v. Muscoda Local 123, 321 U.S. 590, 598, 64 S. Ct. 698 (1944) (defining work as “physical or mental exertion (whether burdensome or not) controlled or required by the employer and pursued necessarily and primarily for the benefit of the employer and his business”).
The Washington Administrative Code defines “work” under WAC 296-126-002(8), as “hours worked” as “all hours during which the employee is authorized or required by the employer to be on duty on the employer’s premises or at a prescribed workplace.”
Several notable companies have been sued for failing to pay overtime for smartphone use after hours, namely Verizon, T-Mobile and Black and Decker. Set for trial in August 2015, a Chicago police sergeant has filed suit against the City of Chicago alleging that he was required to respond to emails and text messages while off duty, but without receiving overtime.
While there have been relatively few of these types of smartphone/after-hours cases, this may change following revision of the Department of Labor rules expected for release and public comment any day now.
 Applied in Stevens v. Brink’s Home Security, Inc., 162 Wn.2d 42, 48-50, 169 P.3d 473(2007), Mechanics were engaged in “work” when they drove company vans from their home to the first customer at shift’s start and drove from the last customer to home at shift’s end.