It is not often that long-standing laws cause a federal court to throw up its arms, but for the second time in little over a year, the Ninth Circuit Court of Appeals has done just that in attempting to understand a California employment law.

Last year, the Ninth Circuit threw up its hands and asked the California Supreme Court to clarify California’s obscure “suitable seating” laws.

Now, in Mendoza v. Nordstrom, Inc., the Ninth Circuit has thrown up its hands again, this time asking the California Supreme Court to clarify California’s day-of-rest laws.

The Ninth Circuit has held that the statutory language in those laws is ambiguous, and the interpretation of certain words such as “any” or “cause” could lead to very different conclusions – and very different liability findings. Assuming the California Supreme Court accepts the challenge, its decision could have a huge impact on how employers set employee schedules or permit employees to swap shifts. And it could walk many employers right into wage-hour class actions based upon their past practices and interpretation of those terms.

Specifically, rather than try to interpret the statutory language itself, the Ninth Circuit has asked the California Supreme Court to answer the following three questions:

(1) With regard to California Labor Code section 551, which  provides that “[e]very person employed in any occupation of labor is entitled to one day’s rest therefrom in seven,” is the required day of rest calculated by the workweek, or is it calculated on a rolling basis for any consecutive seven-day period? As the Court noted, this is no mere matter of semantics. One answer would lead to liability for the employer, while the other would not.

(2) With regard to California Labor Code section 556, which exempts employers from providing such a day of rest when the total hours of employment do not exceed 30 hours in any week or six hours in “any” one day thereof, does the exemption apply when an employee works less than six hours in any one day of the applicable week, or does it apply only when an employee works less than six hours in each day of the week? As the Court noted, the word “any” could support either interpretation. And, again, this is not a matter of semantics. The different interpretations of “any” would lead to very different liability determinations.

(3) With regard to California Labor Code section 552, which provides that an employer may not “cause” his employees to work more than six days in seven, what does the word “cause” mean? Does it mean “force, coerce, pressure, schedule, encourage, reward, permit, or something else?” Again, the different interpretations of “cause” will lead to different liability determinations.

The California Supreme Court’s anticipated answers to these questions could have a huge impact upon employers in California, particularly in the hospitality and retail industries where it is not uncommon to schedule employees to work seven days or more in a row with shifts of varying lengths, and where employees may often swap shifts with each other such that they are working seven days or more in a row. Should the Supreme Court rule, for instance, that it is unlawful to permit employees to work seven days in a row spanning two workweeks, even where the employees wish to do so, employers will need to change their practices going forward to ensure that does not occur – and they may face class action lawsuits for permitting it to occur in the past.