Appellant, the employee-
claimant, appeals from the decision of the Arkansas Workers’ Compensation Commission finding that he failed to meet his burden of proving by a preponderance of the evidence that marijuana did not substantially occasion his injury. He contends that the Commission’s decision was not supported by substantial evidence. We affirm the Commission’s decision.
A compensable injury does not include an “[ijnjury where the accident was substantially occasioned by” the use of illegal drugs. Ark. Code Ann. § ll-9-102(4)(B)(iv)(hJ (Supp. 2007). Further, the “presence” of illegal drugs “shall create a rebuttable presumption that the injury or accident was substantially occasioned by” the use of illegal drugs. Ark. Code Ann. § 11 — 9— 102(4)(B)(iv)[6/). And finally, an “employee shall not be entitled to compensation unless it is proved by a preponderance of the evidence that the . . . illegal drugs. . . did not substantially occasion the injury or accident.” Ark. Code Ann. § 11-9-102(4) (B)(iv)(d).
On appeal, we view the evidence in a light most favorable to the Commission’s decision and affirm if the decision is supported by substantial evidence. Woodall v. Hunnicutt Constr., 340 Ark. 377, 12 S.W.3d 630 (2000). When, as here, the Commission denies coverage because the claimant failed to meet his burden of proof, the substantial-evidence standard of review requires that we affirm the Commission’s decision if its opinion displays a substantial basis for the denial of relief. Id. Substantial evidence is such relevant evidence as a reasonable mind might accept as adequate to support a conclusion. Id. It is the function of the Commission to determine the credibility of the witnesses and the weight to be given to their testimony. Id. Whether the rebuttable presumption is overcome by the evidence is a question of fact for the Commission to determine. Id.
According to the decision of the administrative law judge (ALJ), whose opinion was adopted by the Commission, an employee-employer-carrier relationship existed on January 25, 2005, when appellant suffered an injury resulting in the amputation of the fingers of his left hand as well as a portion of that hand. The injury occurred during the operation of a press used in the manufacture of gun magazines. During the operation of the press, one person feeds metal into the press, a second operates the press by pressing two buttons simultaneously, and a third catches the product after it is stamped out by the press. Though appellant normally worked in another department, around 11:00 a.m. that day, he was asked to help operate the press by catching the finished product as it was stamped out by the press. Craig Westbrook demonstrated the task to appellant and then observed appellant as he also performed the task. According to appellant, Westbrook instructed him never to put his hand in the press.
Appellant worked at the press for approximately one hour, and after a lunch break, continued to perform his job. But during operation of the press after lunch, material placed in the press became snagged. After the problem was corrected, the press was restarted, and appellant, whose hand was in the press, was injured. Approximately twenty-five hours after the injury, a urine sample was taken from appellant, which showed the presence of marijuana metabolites in an amount greater than 500 ng/mL.
Appellant’s expert witness testified that while the urine test does indicate the presence of marijuana metabolites, it does not indicate when appellant used the marijuana, nor whether appellant was impaired at the time of the accident. Appellees’ expert witness, however, testified that a report of more than 100 ng/mL of marijuana metabolites in the urine demonstrated an 83% likelihood that the blood level of the THC active compound was above 1 ng/mL, and that this would demonstrate an impaired condition. Further, he testified that given that the level was greater than 500 ng/mL, there would be more than a 95% chance that claimant was impaired at the time of his injury, which would affect judgment, reaction time, perception, cognitive function, and motor control.
In its decision, the Commission adopted the ALJ’s decision, which accorded great weight to the testimony of appellees’ expert witness. Furthermore, the Commission considered appellant’s testimony that he had not smoked marijuana for six days and found that it was not credible, noting that appellant admitted to smoking two to four marijuana cigarettes a day and that he had been smoking marijuana for the five years prior to the accident. Also, the Commission noted that appellant’s own expert witness indicated that appellant probably had smoked marijuana within the three or four days prior to the accident, that someone with 500 ng/mL of marijuana metabolites should not work around a press, and that appellant’s act of putting his hand in the press despite instructions to the contrary could be consistent with short-term memory loss caused by marijuana. Further, the Commission discounted the testimony of the three witnesses who were present on the day of the injury and who indicated that appellant had not been acting impaired that day.
Appellant challenges the Commission’s order. He asserts that the presence of metabolites does not create a rebuttable presumption that the injury or accident was substantially occasioned by the use of illegal drugs, and he relies on his own expert witness’s testimony that one could not determine, based on a urine test indicating the presence of metabolites, whether appellant was impaired. He attacks the testimony of appellees’ expert witness, contending that it was speculative and not stated with any degree of certainty. Further, he contends that the accident occurred because of his lack of experience and knowledge about the press, and that the direct cause of his injury was the other employee’s act of pressing the two buttons to activate the press, when it should have been apparent to him that appellant’s hand was not clear of the machine. He also observes that none of the witnesses testified that appellant seemed impaired.
This court has previously concluded that testing positive for marijuana metabolites is sufficient to establish a rebuttable presumption that the employee’s injury was substantially occasioned by the use of marijuana. Wood v. West Tree Service, 70 Ark. App. 29, 14 S.W.3d 883 (2000); see also Flowers v. Norman Oaks Constr. Co., 341 Ark. 474, 17 S.W.3d 472 (2000) (noting that both the Arkansas Supreme Court and this court have held that the presence of drugs or alcohol established only by metabolites or a slight amount of drugs or alcohol was sufficient to raise the rebuttable presumption and shift the burden of proof to the claimant to rebut the presumption). Moreover, in this case, appellees’ expert witness testified that the levels of metabolites in appellant’s urine demonstrated that appellant had the THC active compound in his blood. Accordingly, we are compelled to conclude that the rebuttable presumption was created.
As for his assertion that we should not credit the testimony of appellees’ expert witness, we observe that the Commission was faced with competing expert testimony, and as noted above, it is the Commission’s function to weigh the testimony. The Commission gave greater weight to the appellees’ expert witness, who opined that there was a 95% chance that appellant was impaired at the time of the accident, and we cannot say that the testimony was, as appellant contends, not substantial.
Finally, appellant asserts that there were other factors that could have independently caused the injury. As noted above, the employee must prove by a preponderance of the evidence that the illegal drugs did not substantially occasion the injury or accident. Ark. Code Ann. § ll-9-102(4)(B)(iv)(d). The phrase “substantially occasioned” by the use of illegal drugs requires that there be a direct causal link between the use of the drugs and the injury in order for the injury to be noncompensable. ERC Contractor Yard & Sales v. Robertson, 335 Ark. 63, 977 S.W.2d 212 (1998). Here, the Commission credited the testimony that appellant was impaired, that he placed his hand in the press despite instruction to the contrary, and that this was consistent with appellant having impaired judgment from intoxication from marijuana. Thus, we conclude that the Commission’s opinion displays a substantial basis for the denial of relief, as it could conclude that appellant failed to prove that his use of illegal drugs did not substantially occasion his injury.
Affirmed.
Pittman, C.J., and Gladwin, Robbins, and Bird, JJ., agree. Griffen, J., dissents.