What is one condition under which lawful deductions from an employee's salary can occur?

Lawful deductions from an employee's salary can occur when they are authorized by law. This means that specific deductions are dictated by legal requirements, such as federal or state taxes, Social Security contributions, unemployment insurance, or court-ordered garnishments. Laws exist to protect employees by regulating what can be deducted and ensuring that any such deductions are appropriate and justifiable under the law.

The other choices do not provide lawful grounds for salary deductions. Poor employee performance may lead to disciplinary actions but does not equate to lawful deductions from wages. Employer discretion suggests a lack of legal basis for deductions, which can lead to potential violations of labor laws. Lastly, deductions during layoffs are not universally permissible and depend on specific contractual agreements or regulations, making this option insufficient on its own.