Jerry and Joanne Brinkley bring consolidated appeals from (1) an order of the Industrial Commission that Jerry Brinkley was injured while acting within the scope of his employment for Basin Land Irrigation Company, and (2) from a summary judgment order of the district court which deferred to the Industrial Commission’s determination as a basis for dismissing plaintiff’s complaint against Basin Land Irrigation Company (Basin Land).
Brinkley was employed by both Basin Land and Hat Butte Canal Company (Hat Butte). The two companies had an arrangement whereby Basin Land paid 35% and Hat Butte paid 65% of all of Brinkley’s expenses, workers’ compensation premiums and salary as a common ditch rider for both companies.
On September 1, 1984, Harold Breach (president of Basin Land), operating in the scope of his employment, was in an automobile accident with Brinkley which caused Brinkley’s injury. Brinkley testified that on the morning of the accident he left his home and was headed west on Bigfoot Road to work at the relift station that was part of the Hat Butte Canal system, which station had nothing to do with the Basin Land system. Brinkley further testified that after he finished checking the relift station that he was going to check a Hat Butte pond further north and then he was planning to return home.
Harold Breach’s son, Mike, testified that on August 31, he telephoned Jerry Brinkley’s home to order water to be applied for Basin Land on September 1. Mike Breach testified that he talked with Brinkley’s daughter but not with Brinkley himself. Brinkley and members of his family testified that no communication of any sort was received from Mike Breach regarding any water orders for Basin Land for September 1. The Commission, unable to determine from the evidence that Brinkley was in fact specifically engaged in services for Basin Land at the time of the accident, nevertheless ruled that Brinkley was an employee of Basin Land upon the following three-step analysis:
First, the Commission stated:
“While it may be true that at the time of the accident Brinkley had received no instructions to charge the Basin Land system, it seems highly unlikely that he would have passed the entire day without performing services on behalf of Basin Land____ Although the evidence suggests that Brinkley was bound for a location on the Hat Butte system, it cannot be said that Basin Land retained no power to direct or control Brinkley.”
Secondly, the Commission held that since Brinkley was not performing duties specific to his Hat Butte employment and he was subject to the direction and control of either employer at all times, then the “requirement that the accident be clearly identifiable with a particular employer is not met,” the Commission citing Newman v. Bennett, 512 P.2d 497 (Kan.1973); Gropp v. Pluid, 91 Idaho 722, 429 P.2d 852 (1967); Pinson v. Minidoka Highway District, 61 Idaho 731, 106 P.2d 1020 (1940).
*123Thirdly, the Commission reasoned and ruled from its first two premises that since Brinkley did not meet his burden of proving that his employment was “clearly identifiable” with Hat Butte, he would be considered to be employed by both companies at the time of the accident.
This appeal presents two issues, the first being whether the Commission erred in placing the burden of proof on Brinkley to establish the employer/employee relationships. The second issue is whether the trial court correctly determined that it was required to defer to the Commission’s determination of the first issue.
I.
We first address the jurisdictional issue. Either the district court or the Industrial Commission has the jurisdiction to determine the employer/employee relationship and the tribunal where the issue is first raised shall prevail. In Anderson v. Gailey, 97 Idaho 813, 825, 555 P.2d 144, 156 (1976), this Court specifically held:
[I]f the notice of injury was filed with the Industrial Commission before the plaintiffs filed their original complaint with the district court, then the Industrial Commission has the first right to determine the jurisdictional issue, and its determination is res judicata upon the question of jurisdiction and the factual questions upon which the determination of jurisdiction must necessarily turn. Id.
Both Brinkley and Hat Butte promptly filed their respective notices of injury in September. Brinkley did not file a civil complaint against Breach until February of the following year. Neither of the notices of injury, however, mentioned Basin Land as the employer. Thus, the Commission erred when it determined that the race to decide jurisdiction was settled by the September notices, since those notices were in no way applicable to the employment relationship, if any, between Brinkley and Basin Land. As established by Anderson, the race to file first is between the parties in contention and nothing was filed by either Brinkley or Basin Land to establish the existence of a workers’ compensation issue between them until much later than the September notices of injury.
The record establishes, however, that the Industrial Commission nevertheless had the jurisdiction to determine the issue because of pleadings filed with it later. In June of 1985, Basin Land filed a formal application for hearing with the Commission to specifically determine Brinkley’s employment status at the time of the accident. Basin Land never filed a notice of injury at any time after Brinkley’s injury. Brinkley’s complaint, filed with the district court in February, had not mentioned Basin Land as a party to the action. It was not until August, 1985, that Brinkley amended his complaint to add Basin Land as a defendant. Therefore, Basin Land won the race to file since its application for hearing preceded Brinkley’s amended complaint, the result being that the Commission had properly entertained adjudication of the issue of the employer/employee relationships.
II.
We turn now to the central issue, that is, whether the Commission correctly held that Brinkley did not meet his burden of establishing that his accident was “clearly identifiable” with his Hat Butte employment. Generally, a claimant before the Industrial Commission is the injured employee. In this case, however, Basin Land was the claimant (i.e., the moving party). Basin Land was attempting to use the Workers’ Compensation Law as a shield to avoid third-party tort liability. If it were established that Brinkley was injured in the course of his employment with Basin Land, the workers’ compensation statutes would provide immunity to Basin Land against the tort claim in district court.
Although there is nothing improper about an employer using the Workers’ Compensation Law as a defense against civil tort liability, the Industrial Commission erred in saddling Brinkley with the burden of proof since Basin Land was the claimant:
*124A claimant in a workmen’s compensation cause has the burden of proving compensable disablement, caused by an accident arising out of and in the course of his employment. His proof must establish a “probable, not merely a possible, connection between cause and effect to support his contention that he suffered a compensable accident.”
Kern v. Shark, 94 Idaho 69, 71, 480 P.2d 915, 917 (1971) (quoting Davenport v. Big Tom Breeder Farms, Inc., 85 Idaho 604, 609, 382 P.2d 762, 764 (1963).) Callantine v. Blue Ribbon Linen Supply, 103 Idaho 734, 653 P.2d 455 (1982); see also, Neufeld v. Browning Ferris Industries, 109 Idaho 899, 712 P.2d 600 (1985). Although the above precedent is couched in language directed towards employees as claimants, the critical language is that the claimant has the burden of proof. The instant case is unique in that rarely does an employer come before the Industrial Commission as a claimant. One of the fundamental rules of procedure is that the party seeking affirmative relief has the burden of proof. Woodruff v. Butte & Mkt. L. C. Co., 64 Idaho 735, 137 P.2d 325 (1943); Kingsford v. Bennion, 68 Idaho 501, 199 P.2d 625 (1948) (overruled on other grounds in Smith v. Daniels, 93 Idaho 716, 471 P.2d 571 (1970)).
The Commission was correct in stating that the accident must be “clearly identifiable” with a particular employer. Newman, supra. The burden is on the claimant Basin Land, however, to prove by a preponderance of the evidence that Brinkley was operating in the scope of his employment with Basin Land when the accident occurred. If Basin Land fails to meet its burden, then the workers’ compensation laws do not apply and Brinkley is free to pursue a third-party civil action against Basin Land and Harold Breach in district court. See I.C. § 72-211 and § 72-223.
Finally, it must be pointed out that the Commission’s analysis regarding the status of Brinkley’s employment was somewhat skewed. As noted above, the Commission held that Brinkley was not performing duties specific to his Hat Butte employment and he was subject to the direction and control of either employer at all times.
Given the unique character of Brinkley’s employment situation, the Commission nad some concern whether he was a joint or a dual employee of the two employers. The Commission cited to 1C Larson, Workmen’s Compensation Law 48.4 at 8-511:
Joint employment occurs when a single employee, under contract with two employers, and under the simultaneous control of both, simultaneously performs services for both employers, and when the service for each employer is the same as, or is closely related to, that for the other. In such a case, both employers are liable for workmen’s compensation. Dual employment occurs when a single employee, under contract with two employers, and under the separate control of each, performs services for the most part for each employer separately, and when the service for each employer is largely unrelated to that for the other. In such a case, the employers may be held liable for workmen’s compensation separately or jointly, depending on the severability of the employee’s activity at the time of injury.
The Industrial Commission held that Brinkley generally performed services which benefitted one of his employers at any given time and the “dual employment relationship is most applicable.” The Commission ultimately held that Brinkley was merely “driving” to a location accessible to either employment and that he did not meet his burden that the accident be clearly identifiable with a particular employer. Yet, the Commission ignored another of its findings that “it may be true that at the time of the accident Brinkley had received no instructions to charge the Basin Land system____”
It is Basin Land’s duty to prove that Brinkley was working for Basin Land when the accident occurred — not Brinkley’s duty to prove that he was working for Hat Butte. Brinkley should have been under no duty to prove that he was performing duties for Hat Butte, since the pertinent issue regarding workers’ compensation cov*125erage was whether he was working for Basin Land at the time of the accident. Secondly, the fact that Brinkley was subject to the direction and control of either employer at moment’s notice is not determinative. What Basin Land must prove as claimant is that Brinkley’s injury arose out of and in the course of his employment with Basin Land. Beebe v. Horton, 77 Idaho 388, 293 P.2d 661 (1956); Neufeld v. Browning Ferris, supra.
Reversed and remanded to the Industrial Commission for further proceeedings, including entry of new findings of fact and conclusions of law and order consistent herewith. Costs to appellant, no attorney fees awarded.
SHEPARD, C.J., and BISTLINE, J., concur. DONALDSON, J., sat, but did not participate due to his untimely death.