The “unavoidable accident” defense in negligence actions has roots dating back to the early 20th century in Idaho.1 It is generally defined as an unforeseeable and unavoidable event that was not caused by a negligent act or omission of any party in the lawsuit.2 For example, if there was evidence of uncertain weather conditions at the time of an accident, trial courts would often allow unavoidable accident jury instructions.3 The instruction was also allowed in cases where a motor vehicle broke down in the middle of the road due to a mechanical malfunction the defendant driver did not know about and could not reasonably expect.4


Negligence is never presumed, but must be proven, and it is possible, under the laws of this State, for an accident to occur without wrongful acts on the part of either plaintiff or defendant. Such a collision comes under the heading of an unavoidable accident, and if you find that neither plaintiff nor the driver of any other car who is a party to this action was guilty of such wrongful conduct as would constitute negligence in this case, then I instruct you that the accident would be an unavoidable one for which no one would be responsible.5


However, early Idaho Supreme Court decisions noted other jurisdictions were raising concerns with the propriety of giving an unavoidable accident instruction to a jury because it “is nothing more than a denial by the defense of negligence . . . Since the ordinary instructions on negligence and proximate cause sufficiently show that the plaintiff must sustain his burden of proof on these issues in order to recover, the instruction on an unavoidable accident serves no useful purpose.”6 In 1968, jury instructions on the unavoidable accident defense reached a breaking point as the Idaho Supreme Court determined they were “confusing, and misleading, and thus error.”7 The Court further held:

Instructions on negligence and contributory negligence are sufficient and inclusive of the essence of so-called unavoidable accidents; to instruct specifically on unavoidable accidents serves only to inform the jury twice that the plaintiff cannot recover unless he proves negligence. Such instructions serve as well to suggest to the jury a separate defense for the defendant. To the extent that we have heretofore refused to reverse a decision on the basis of the giving of an unavoidable accident instruction, due to the particular factual circumstances of the case, those previous pronouncements are overruled.

While a jury instruction on the unavoidable accident defense is no longer permitted in Idaho, it is important to remember the underlying premise: in order to recover based on a negligence cause of action, a lack of due or proper care on the part of the defendant is an essential element that must be proven by an injured party. “No person is an absolute insurer of the person’s actor or of the safety of others, nor is a person an absolute insurer of the property of others.”8 There must be an act or omission by another that involves a lack of due or proper care before a cause of action for negligence can arise.9 In other words, “the innocence of the person injured does not necessarily establish the negligence of the defendant.”10


  • The unavoidable accident theory may be raised as a defense to a negligence cause of action today, however, the defense is no longer a separate legal doctrine in Idaho.
  • Instead, it is a general defense to a negligence cause of action and is now a fact pattern analysis performed when determining whether an accident occurred with or without negligence by a party.11

Please contact a Gjording Fouser lawyer at 208.336.9777 if you would like any additional information about this topic or any other issues facing your company.

1 Younie v. Blackfoot Light & Water Co., 15 Idaho 56 (1908) (“The defendant denied the material allegations of the complaint, and set up, as a further defense, that the damage was caused by unavoidable accident, and by the negligence of plaintiff himself.”)

2 Schaub v. Linehan, 92 Idaho 332, 334 (1968).

3 Turner v. Purdum, 77 Idaho 130, 141, 289 P.2d 608, 613 (1955), overruled in part by Schaub v. Linehan, 92 Idaho 332, 442 P.2d 742 (1968) ; Lallatin v. Terry, 81 Idaho 238, 249, 340 P.2d 112, 119 (1959), overruled in part by Schaub v. Linehan, 92 Idaho 332, 442 P.2d 742 (1968).

4 Nelson v. Inland Motor Freight Co., 60 Idaho 443, 92 P.2d 790, 792 (1939)

5 Morford v. Brown, 85 Idaho 480, 489, 381 P.2d 45, 50 (1963), overruled in part by Schaub v. Linehan, 92 Idaho 332, 442 P.2d 742 (1968).

6 Lallatin v. Terry, 81 Idaho 238, 249, 340 P.2d 112, 120 (1959), overruled in part by Schaub v. Linehan, 92 Idaho 332, 442 P.2d 742 (1968).

7 Schaub, 92 Idaho at 336.

8 “Lack of care as element of actionable negligence,” 65 C.J.S. Negligence § 2.

9 Id.

10 Id.

11 See Basic American , Inc. v. Shatila, 133 Idaho 726, 741 (1999); Stoddard v. Nelson, 99 Idaho 293, 296 (1978).