The Fair Labor Standards Act (FLSA) requires the payment of a minimum wage, as well as overtime compensation at a rate of not less than one and one-half times an employee's hourly rate for hours worked in excess of a 40-hour workweek. While the FLSA exempts some employees from these requirements based on their job duties or because they work in specified industries, most employees must be paid in accordance with the statute's requirements for work performed. The increased use of personal data assistants (PDAs) and smartphones by employees outside of a traditional work schedule has raised questions about whether such use may be compensable under the FLSA. As PDAs and smartphones provide employees with mobile access to work email, clients, and co-workers, as well as the ability to create and edit documents outside of the workplace, it may be possible to argue that non-exempt employees who perform work-related activities with these devices should receive overtime if such activities occur beyond the 40-hour workweek. This report reviews the FLSA's overtime provisions and examines some of the U.S. Supreme Court's seminal decisions on work. Although PDAs and smartphones provide a new opportunity to consider what constitutes work for purposes of the FLSA, the Court's past FLSA decisions, including those involving on-call time, may provide guidance on how courts could evaluate overtime claims involving the new devices. Section 7(a)(1) of the FLSA, states, in relevant part, [N]o employer shall employ any of his employees who in any workweek is engaged in commerce or in the production of goods for commerce, or is employed in an enterprise engaged in commerce, or in the production of goods for commerce, for a workweek longer than forty hours unless such employee receives compensation for his employment in excess of the hours above specified at a rate not less than one and one-half times the regular rate at which he is employed. The term "employ" is defined by the FLSA to mean "to suffer or permit to work." The term "work," however, is not defined by the statute. In 1944, the Supreme Court sought to clarify the meaning of that term in Tennessee Coal, Iron & Railroad Co. v. Muscoda Local No. 123 , a case involving miners who travelled daily to and from the working face of underground iron ore mines. Muscoda Local No. 123 and two other unions representing the miners maintained that the workers' hours of employment should include the travel time, and that the miners were entitled to overtime compensation because their hours of employment exceeded the statutory maximum workweek. Without a statutory definition for "work," the Court in Tennessee Coal relied on the plain meaning of the term to conclude that the miners' travel time should be construed as work or employment for purposes of the FLSA. The Court noted, "[W]e cannot assume that Congress here was referring to work or employment other than as those words are commonly used—as meaning 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 Court maintained that the dangerous conditions in the mine shafts provided proof that the journey to and from the working face involved continuous physical and mental exertion. In addition, the miners' travel to and from the working face was not undertaken for the convenience of the miners, but was performed for the benefit of the mining companies and their iron ore mining operations. In Armour v. Wantock , the Court clarified that actual physical or mental exertion was not necessary for an activity to constitute work under the FLSA. In Armour , a group of fire guards who remained on call on the employer's premises contended that they were entitled to overtime compensation for their on-call time. Although the employer attempted to make this time tolerable by providing beds, radios, and cooking equipment, the Court found that the guards were entitled to overtime compensation. The Court observed the following: Of course an employer, if he chooses, may hire a man to do nothing, or to do nothing but wait for something to happen. Refraining from other activity often is a factor of instant readiness to serve, and idleness plays a part in all employments in a stand-by capacity. Readiness to serve may be hired, quite as much as service itself, and time spent lying in wait for threats to the safety of the employer's property may be treated by the parties as a benefit to the employer. Whether time is spent predominantly for the employer's benefit or for the employee's is a question dependent upon all the circumstances of the case. In Anderson v. Mt. Clemens Pottery , a 1946 case involving workers at a pottery plant and the computation of compensable work time, the Court concluded that time spent walking to a work area on the employer's premises after punching a time clock was compensable. The Court indicated that because the statutory workweek includes all time that an employee is required to be "on the employer's premises, on duty, or at a prescribed workplace," the time spent in these activities must be compensated. Other preliminary activities, such as putting on aprons and preparing equipment, were also found to be compensable because they were performed on the employer's premises, required physical exertion, and were pursued for the employer's benefit. At the same time, however, the Court in Mt. Clemens Pottery recognized "a de minimis rule" for activities that involve only a few seconds or minutes of work beyond an employee's scheduled work hours. The Court explained that "[i]t is only when an employee is required to give up a substantial measure of his time and effort that compensable working time is involved." Fearing that Mt. Clemens Pottery would subject employers to significant and "wholly unexpected" financial liabilities, Congress passed the Portal-to-Portal Act, which abolished all claims for unpaid minimum wages and overtime compensation related to activities engaged in prior to May 14, 1947. The Portal-to-Portal Act also provided prospectively that an employer would not be subject to liability under the FLSA for failing to pay a minimum wage or overtime compensation for travel to and from the place where an employee's principal activity or activities are performed, or for activities that are "preliminary to or postliminary to [those] principal activity or activities." The Court's recognition of a de minimis rule and the enactment of the Portal-to-Portal Act have been viewed as attempts to limit the broad definition of "work" established in Tennessee Coal . Even after the Portal-to-Portal Act's enactment, however, the Court continued to find certain preparatory and concluding activities to be compensable under the FLSA. In Steiner v. Mitchell , for example, the Court found that the time spent by workers in a battery plant changing clothes at the beginning of a shift and showering at the end of a shift was compensable work time under the FLSA. Citing a colloquy between several senators and one of the sponsors of the Portal-to-Portal Act, the Court maintained that Congress did not intend to deprive employees of the benefits of the FLSA if preliminary or postliminary activities are an integral and indispensible part of the principal activities for which they are employed. In IBP v. Alvarez , the Court further concluded that the time spent walking between a changing area where protective clothing was put on and taken off and a work area was also compensable time under the FLSA. Whether non-exempt workers may be entitled to overtime compensation for work activities performed using a PDA or smartphone beyond a 40-hour workweek will probably depend on the facts of each case. At a minimum, an employee seeking such compensation will likely have to establish that he was engaged in compensable work. The factors articulated by the Court in Tennessee Coal continue to be recognized as a starting point for determining whether an employee's activities constitute work under the FLSA. First, does use of a PDA or smartphone require physical or mental exertion? Second, is the use of a PDA or smarthphone controlled or required by the employer? Finally, is the use of a PDA or smartphone necessarily and primarily for the benefit of the employer and his business? While the facts of each case will ultimately determine whether the Tennessee Coal factors are satisfied, it seems possible that at least some PDA or smartphone use could be viewed as compensable work under the FLSA. Even with the Court's reconsideration in Armour of the need for physical or mental exertion to constitute work, it appears reasonable to conclude that at least some PDA or smartphone use will require mental exertion. An employee responding to work email or reviewing or editing documents is arguably engaged in mental exertion. Further, providing PDAs and smartphones to non-exempt employees without any statement or policy about not using the devices outside of regular work hours may lead to the conclusion that their use is controlled or required by the employer, particularly if supervisors or senior employees send messages or documents with the expectation that they will be immediately read or reviewed. Finally, because employers could benefit from an employee's response to email or his review of a document after regular work hours, it could be argued that the employee's PDA or smartphone use is necessarily or primarily for the benefit of the employer and his business. The absence, however, of any significant case law involving the FLSA and PDA or smartphone use makes it difficult to know exactly how courts will evaluate related claims for overtime compensation. Some believe that cases involving on-call time could be instructive, particularly because they present an analogous situation in which an employee is kept in constant contact with the employer. In Skidmore v. Swift & Co ., one of the Court's early cases involving on-call time and the payment of overtime compensation, the Court indicated that the law does not preclude "waiting time from also being working time."