Miss. Code Ann. § 71-3-121

(1) In the event that an employee sustains an injury at work or asserts a work-related injury, the employer shall have the right to administer drug and alcohol testing or require that the employee submit himself to drug and alcohol testing. If the employee has a positive test indicating the presence, at the time of injury, of any drug illegally used or the use of a valid prescription medication(s) taken contrary to the prescriber's instructions and/or contrary to label warnings, or the use of medical cannabis in accordance with the Mississippi Medical Cannabis Act and rules and regulations adopted thereunder, or eight one-hundredths percent (.08%) or more by weight volume of alcohol in the person's blood, it shall be presumed that the proximate cause of the injury was the use of a drug illegally, or the use of a valid prescription medication(s) taken contrary to the prescriber's instructions and/or contrary to label warnings, or the use of medical cannabis in accordance with the Mississippi Medical Cannabis Act and rules and regulations adopted thereunder, or the intoxication due to the use of alcohol by the employee. If the employee refuses to submit himself to drug and alcohol testing immediately after the alleged work-related injury, then it shall be presumed that the employee was using a drug illegally, or was using a valid prescription medication(s) contrary to the prescriber's instructions and/or contrary to label warnings, or the use of medical cannabis in accordance with the Mississippi Medical Cannabis Act and rules and regulations adopted thereunder, or was intoxicated due to the use of alcohol at the time of the accident and that the proximate cause of the injury was the use of a drug illegally, or the use of a valid prescription medication(s) taken contrary to the prescriber's instructions and/or contrary to label warnings, or the use of medical cannabis in accordance with the Mississippi Medical Cannabis Act and rules and regulations adopted thereunder, or the intoxication due to the use of alcohol of the employee. The burden of proof will then be placed upon the employee to prove that the use of drugs illegally, or the use of a valid prescription medication(s) taken contrary to the prescriber's instructions and/or contrary to label warnings, or the use of medical cannabis in accordance with the Mississippi Medical Cannabis Act and rules and regulations adopted thereunder, or intoxication due to the use of alcohol was not a contributing cause of the accident in order to defeat the defense of the employer provided under Section 71-3-7 .

(2) The results of the drug and alcohol tests, employer-administered or otherwise, shall be considered admissible evidence solely on the issue of causation in the determination of the use of drugs illegally, or the use of a valid prescription medication(s) taken contrary to the prescriber's instructions and/or contrary to label warnings, or the use of medical cannabis in accordance with the Mississippi Medical Cannabis Act and rules and regulations adopted thereunder, or the intoxication due to the use of alcohol of an employee at the time of injury for workers' compensation purposes under Section 71-3-7 .

(3) No cause of action for defamation of character, libel, slander or damage to reputation arises in favor of any person against an employer under the provisions of this section.