Edwin H. Barker was an electrician employed by Fischbach & Moore, Inc. Pursuant to a contract executed between the employer and Barker’s union, Barker received $90 per week as a travel allowance for travel between his home in Twin Falls and the work site, which was located 26 miles east of Arco.
At approximately 12:00 noon on April 25, 1980, Barker left the work site to travel to a dentist appointment in Twin Falls. En route to the dentist’s office, Barker was involved in a single car accident that resulted in his death.
Barker’s wife then filed a claim for workmen’s compensation death benefits, alleging that Barker’s death had arisen out of or *872during the course of his employment.1 The Industrial Commission denied benefits after concluding that Barker had left the work site and was not engaged in his employment at the time of the accident.
On appeal, this Court reversed. Barker v. Fischbach & Moore, Inc., 105 Idaho 108, 666 P.2d 635 (1983) (Barker I). In Barker I this Court acknowledged that Spanbauer v. Peter Kiewit Sons’ Company, 93 Idaho 509, 465 P.2d 633 (1970), might appear to hold that the evidence concerning the distance traveled to and from work and the amount of travel expenses paid by the employer is irrelevant in deciding whether or not the exception to the coming and going rule should apply. However, the Court in Barker I clarified Spanbauer, stating that “it is now necessary for this Court to emphasize that Spanbauer is to be read that the payment of travel expenses, along with other evidence indicating the employer intended to compensate the employee for travel time, will justify expanding the course of employment to include going to and from work.” After thus clarifying Spanbauer, the Barker I Court remanded the case to the Industrial Commission “to determine if other evidence, besides the payment of travel expenses, exists to support a finding that the employee was within the course of employment at the time of the accident.”
On remand, no additional evidence was submitted to the Industrial Commission by the parties. The commission re-examined the record and the written arguments submitted by the parties and issued a decision in which it again denied benefits. The commission concluded that it could “find no evidence, other than the actual payment itself, to indicate that the employer intended to compensate the employee for travel time or travel expense. The commission therefore concludes that its original decision dismissing the claimant’s claim and denying benefits was correct and hereby affirm said decision.”
Idaho Constitution, art. 5, § 9, limits this Court’s review of Industrial Commission decisions to a review of questions of law. We are required to uphold all factual findings made by the Industrial Commission if those findings are supported by substantial, competent evidence. In re Chavez, 104 Idaho 279, 281, 658 P.2d 950, 952 (1983); Case of Graham, 103 Idaho 824, 826, 654 P.2d 1377, 1378-79 (1982). Having fully reviewed the record, we conclude that the Industrial Commission’s finding that the claimant was not within the course and scope of his employment at the time of the accident is supported by substantial and competent evidence.
Furthermore, our review of the record indicates that the Industrial Commission correctly applied the law as stated in Barker I in reaching its decision.
“The rule is well established and long adhered to in this state that where, upon an appeal, the Supreme Court, in deciding a case presented states in its opinion a principle or rule of law necessary to the decision, such pronouncement becomes the law of the case, and must be adhered to throughout its subsequent progress, both in the trial court and upon subsequent appeal ....” Suitts v. First Security Bank of Idaho, 110 Idaho 15, 713 P.2d 1374 (1985) (iquoting from Carlson v. Northern Pacific Rail Co., 86 Mont. 78, 281 P. 913, 914 (Mont.1929).
As we noted in Suitts, the doctrine of law of the case has long been the rule in this jurisdiction. See Palmer v. Dermitt, 102 Idaho 591, 595, 635 P.2d 955, 959 (1981); Creem v. Northwestern Mut. Fire Ass’n of Seattle, Wash., 58 Idaho 349, 352, 74 P.2d *873702, 703 (1937); Unfried v. Libert, 23 Idaho 603, 606, 131 P. 660, 661 (1913); Hall v. Blackman, 9 Idaho 555, 75 P. 608 (1904). In fact, this Court has often compared the doctrine of law of the case with the principle of res judicata, indicating that an appellate court is bound by the law of the case. See Idaho Dept. of Law Enforcement v. One 1955 Willys Jeep, 100 Idaho 150, 157, 595 P.2d 299, 306 (1979) (Bistline, J., dissenting); Creem v. Northwestern Mut. Fire Ass’n of Seattle, Wash., 58 Idaho 349, 358, 74 P.2d 702, 705 (1937) (Ailshie, J., dissenting in part); Hall v. Blackman, 9 Idaho 555, 559-560, 75 P. 608, 609 (1904).
The Industrial Commission correctly applied the law announced by this Court in Barker I to the facts of this case. Accordingly, the order of the Industrial Commission is affirmed; costs to respondent.
. Workmen’s compensation may only be collected by employees who are injured or killed within the course of employment, I.C. § 72-102(14)(a); I.C. § 72-201. The general rule is that a worker traveling to and from an employer’s place of business is not within the course of employment. Clark v. Daniel Morine Constr. Co., 98 Idaho 114, 559 P.2d 293 (1977). However, an exception to this "coming and going” rule is made when there is a special risk or service incident to the employee’s employment involved in his travel. Ridgeway v. Combined Ins. Companies of America, 98 Idaho 410, 565 P.2d 1367 (1977); Jaynes v. Potlatch Forests, 75 Idaho 297, 271 P.2d 1016 (1954).