On November 30, 1968 appellees, Joan LaVerne Henderson, Omarie Henderson, Sharon Marie Hass and James F. Henderson, instituted these actions in the District Court, Oklahoma County, Oklahoma against Roberta Jean Price claiming damages for personal injuries resulting from an automobile collision on December 3, 1966 in Oklahoma City. On January 30, 1969 the United States attorney, for the purpose of removal to the federal court, certified that at the time of the accident Price, the driver of one of the automobiles, was an employee of the United States and acting within the scope of her employment when the collision occurred. After removal, the actions were dismissed as to Price and the United States substituted as the sole defendant. Motions by the United States to dismiss the actions for the reason that the actions were barred by the two-year statute of limitations provided in 28 U. S.C. § 2401(b) were overruled. The several cases were consolidated for trial to the court at the conclusion of which separate judgments for damages were entered for the appellees. The appeals are here on the consolidated record presenting the same issues in each case.

The United States argues that under the provisions of 28 U.S.C. § 2679 the exclusive remedy of the appellees for their injuries was an action against the United States, and that the suits brought in the state court against the employee did not toll the running of the statute of limitations. The purpose of the Federal Torts Claims Act is to make the United States liable in tort to the same extent as a private individual would be under like circumstances. 28 U.S.C. § 1346(b); Beesley v. United States, 364 F.2d 194 (10th Cir. 1966); Government Employees Insurance Company v. United States, 349 F.2d 83 (10th Cir. 1965), cert. denied, 382 U.S. 1026, 86 S. Ct. 646, 15 L. Ed. 2d 539, reh. denied, 383 U.S. 939, 86 S. Ct. 1064, 15 L. Ed. 2d 857; Weaver v. United States, 334 F.2d 319 (10th Cir. 1964). The provisions of 28 U.S.C. § 26791 were designed to insulate an employee of the United States from liability for injuries caused by negligent acts in the operation of a motor vehicle while acting within the course of employment. Vantrease v. United States, 400 F.2d 853 (6th Cir. 1968); Adams v. United States, 241 F. Supp. 383 (S.D.Ill. 1965). The statutory immunity does not extend to injuries caused by the negligent acts of a government employee unless the employee is acting within the scope of his employment. The factual issue as to the nature of the employment activities at the time of the injuries is to be determined by the principles of respondent superior of the jurisdiction where the tort occurred. Williams v. United States, 350 U.S. 857, 76 S. Ct. 100, 100 L. Ed. 761 (1955); Platis v. United States, 409 F.2d 1009 (10th Cir. 1969). The statute requires the Attorney General of the United States to defend any civil action brought against an employee of the United States and provides a procedure for certification and removal of state court actions against an employee to federal court.

Upon removal the action shall be "deemed a tort action brought against the United States * * *." If, after removal, it is determined before trial on the merits that there is no remedy available against the United States, the case shall be remanded to the state court. 28 U.S.C. § 2679(d). The federal court having found that Price was acting within the scope of her employment at the time of the accident, the only cause of action that existed was against the United States. In this situation the United States became a party as a matter of law when the action was filed in the state court, regardless of when it was formally substituted as a party defendant. Reynaud v. United States, 259 F. Supp. 945 (W.D.Mo.1966); Jones v. Polishuk, 252 F. Supp. 752 (E.D.Tenn. 1965); Whistler v. United States,2 252 F. Supp. 913 (N.D.Ind.1966). See also Fancher v. Baker, 240 Ark. 288, 399 S.W.2d 280 (1966); 16 A.L.R. 3d 1383. There was no error in overruling the motion to dismiss.

The United States also contends that the court erred in concluding that the non use of available seat belts by the appellees was not a defense to the action and could only be considered in mitigation of damages. There have been no Oklahoma cases decided dealing with that approach to the "seat belt defense." In such circumstances we have often stated that in the absence of any state court decisions on the question raised, the district court's determination of the state law will not be disturbed on appeal unless clearly erroneous. Freeman v. Heiman, 426 F.2d 1050 (10th Cir. 1970), and cases cited. The district court's determination was not clearly erroneous and is generally supported by the authorities. In Woods v. Smith, 296 F. Supp. 1128, 1129 (N.D.Fla.1969), that court, in attempting to anticipate Oklahoma law on this issue, after a review of the relevant decisions stated:

"* * * I conclude Oklahoma would not allow such failure (non use of seat belts) to be presented either as evidence of contributory negligence, or in mitigation of damages. * * *"

Although the Florida and Oklahoma district courts resolved the issue differently as to the mitigation of damages question, there was total harmony in that the non use of seat belts was not a defense under Oklahoma law, but rather to be viewed, if at all, from the standpoint of proximate cause. See generally 21 Okla.L.R. 88 (1968);3 Miller v. Miller, 273 N.C. 228, 160 S.E.2d 65 (1968); cf. Sams v. Sams, 247 S.C. 467, 148 S.E.2d 154 (1966); 15 A.L.R. 3d 1423.

Affirmed.