While I haven't seen this exact scenario (where a mistake was made on a food order) to a certain degree it is the same as if there is some type of breakage that occurs or a mistake causes a loss of money.
This matter is addressed specifically on the California Department of Industrial Relations (DIR) website. That website states:
Q: If I break or damage company property or lose company money while performing my job, can my employer deduct the cost/loss from my wages?
A. No, your employer cannot legally make such a deduction from your wages if, by reason of mistake or accident a cash shortage, breakage, or loss of company property/equipment occurs. The California courts have held that losses occurring without any fault on the part of the employee or that are merely the result of simple negligence are inevitable in almost any business operation and thus, the employer must bear such losses as a cost of doing business. For example, if you accidentally drop a tray of dishes, take a bad check, or have a customer walkout without paying a check, your employer cannot deduct the loss from your paycheck.
There is an exception to the foregoing contained in the Industrial Welfare Commission Wage Orders that purports to provide the employer the right to deduct from an employee's wages for any cash shortage, breakage or loss of equipment if the employer can show that the shortage, breakage or loss is caused by a dishonest or willful act, or by the employee's gross negligence. What this means is that a deduction may be legal if the employer proves that the loss resulted from the employee's dishonesty, willfulness, or grossly negligent act. Under this regulation, a simple accusation does not give the employer the right to make the deduction. The DLSE has cautioned that use of this deduction contained in the IWC regulations may, in fact, not comply with the provisions of the California Labor Code and various California Court decisions. Furthermore, DLSE does not automatically assume that an employee was dishonest, acted willfully or was grossly negligent when an employer asserts such as a justification for making a deduction from an employee's wages to cover a shortage, breakage, or loss to property or equipment.
Labor Code Section 224 clearly prohibits any deduction from an employee's wages which is not either authorized by the employee in writing or permitted by law, and any employer who resorts to self-help does so at its own risk as an objective test is applied to determine whether the loss was due to dishonesty, willfulness, or a grossly negligent act. If your employer makes such a deduction and it is later determined that you were not guilty of a dishonest or willful act, or grossly negligent, you would be entitled to recover the amount of the wages withheld. Additionally, if you no longer work for the employer who made the deduction and it's decided that the deduction was wrongful, you may also be able to recover the waiting time penalty pursuant to Labor Code Section 203.
You can see that there are some exceptions to the standard rule that an employer cannot deduct the amount from the paycheck but the general answer is they cannot. The proper remedy is to file a complaint with the DIR. The employer is not supposed to retaliate against you for filing a complaint but in reality they often do but just find another reason for doing so. http://www.dir.ca.gov/dlse/dlseRetaliation.html
I realize this is a difficult topic but my explanation is as "to the point" as it is possible to amke it since there are some exceptions allowed.
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