California law requires employers provide employees a 30-minute meal period for every five hours of work. Therefore, any employee who works more than ten hours per day is must also be provided with a second 30-minute meal break. During meal period, employees must be “relieved of all duty” during their meal periods or it is considered an “on-duty” meal period and “counts as time worked.”
However, “on-duty” meal periods are actually a “limited alternative to the off-duty meal period requirement.” They are only permitted if (1) the “nature of the work prevents an employee from being relieved of all duty” and (2) the parties agree to an “on-the-job paid meal period”, evidenced by a written agreement. Additionally, the written agreement must include a statement that “the employee may, in writing, revoke the agreement at any time.” Moreover, a second meal period may not be waived unless the employee works less than twelve hours per day, in which case it can be waived by mutual consent of the parties, but only if the first meal break was not waived.
Furthermore, the employer must be able to prove that an “on-duty” meal period was justified. While California Courts have not ruled on the scope of the “nature of the work” exception, the California Division of Labor Standard Enforcement (DLSE) has found that it applies in at least two categories: “(1) where the work has some particular, external force that requires the employee to be on duty at all times; and (2) where the employee is the sole employee of a particular employer.” The DLSE has also laid out a set of “non-exhaustive factors that should be considered when deciding whether the ‘nature of the work’ exception applies to a specific job:
(1) [T]he type of work, (2) the availability of other employees to provide relief to an employee during a meal period, (3) the potential consequences to the employer if the employee is relieved of all duty, (4) the ability off the employer to anticipate and mitigate these consequences such as by scheduling the work in a manner that would allow the employee to take an off-duty meal period, and (5) whether the work product or process will be destroyed or damages by relieving the employee of all duty.”
Thus, even when an employee works alone, the “nature of the work” exception may still not apply “where the employer may have another qualified representative reasonably available to perform the attending duties required under [federal regulation].” 
Note – Health Care Workers:
There is currently a conflict between Industrial Welfare Commission (IWC) Wage Order No. 5, section 11(D), which permits health care workers to waive one of their two meal periods, even on shifts longer than 12 hours, and California Labor Code section 512(a), which prohibits the waiver of meal periods on any such shift. In February of 2015, a California Court of Appeal held that “section 11(D) is partially invalid to the extent it authorizes health care workers to waived their second meal periods on shifts longer than 12 hours.” However, on May 20, 2015, the California Supreme Court granted a petition for review of the appellate court’s decision.
 Abdullah v. U.S. Sec. Assocs., (9th Cir. 2013) 731 F.3d 952, 958.
 Cal. Labor Code § 512(a).
 Abdullah, supra, 731 F.3d at 959.
 Id. at 959, footnote 12.
 Gerard v. Orange Coast Memorial Medical Center, (2015) 234 Cal.App.4th 285, 293, review granted May 20, 2015, No. S225205, 2015 Cal. LEXIS 3768.
 Gerard v. Orange Coast Memorial Medical Center, No. S225205, 2015 Cal. LEXIS 3768.