Vis major is a greater or superior force; an irresistible force. It may be a loss that results immediately from a natural cause that could not have been prevented by the exercise of prudence, diligence and care. It is also termed as vis divina or superior force.

It is an irresistible violence

Violence

Violence is the use of physical force to apply a state to others contrary to their wishes. violence, while often a stand-alone issue, is often the culmination of other kinds of conflict, e.g...

; inevitable accident

Accident

An accident or mishap is an unforeseen and unplanned event or circumstance, often with lack of intention or necessity. It implies a generally negative outcome which may have been avoided or prevented had circumstances leading up to the accident been recognized, and acted upon, prior to its...

 or act of God

Act of God

Act of God is a legal term for events outside of human control, such as sudden floods or other natural disasters, for which no one can be held responsible.- Contract law :...

. Its nature and power absolutely uncontrollable, for example, the inroads of a hostile army or forcible robberies, may relieve from liability from contract

Contract

A contract is an agreement entered into by two parties or more with the intention of creating a legal obligation, which may have elements in writing. Contracts can be made orally. The remedy for breach of contract can be "damages" or compensation of money. In equity, the remedy can be specific...

.

This term has specific meaning in regard to strict liability

Strict liability

In law, strict liability is a standard for liability which may exist in either a criminal or civil context. A rule specifying strict liability makes a person legally responsible for the damage and loss caused by his or her acts and omissions regardless of culpability...

. Strict liability in the law of torts allows for the accrual of liability against an actor where there is no fault or proximate cause given the damages arose from their participation in an ultrahazardous activity, i.e. blasting, damming of water, etc. However, "vis major" offers an exception to such liability. In Fletcher v. Rylands In the Exchequer Chamber, L.R. 1 Ex. 265, 1866, affirmed in the House of Lords

House of Lords

The House of Lords is the upper house of the Parliament of the United Kingdom. Like the House of Commons, it meets in the Palace of Westminster....

 on appeal in Rylands v. Fletcher L.R. 3 H.L. 330, the exception of vis major is introduced:

"[Defendant] can excuse himself by showing that the escape [of a dangerous substance] was owing to the plaintiff's default; or perhaps that the escape was the consequence of vis major, or the act of God... [emphasis added]" -Blackburn J Fletcher v. Rylands L.R. 1 Ex. 265, 1866.

The existence of vis major, or an act of God, will preclude the use of the theory of strict liability given the impossibility of anticipating such an event. (Think of a dam breaking after a hurricane where there is no negligence found on the part of the owner/operator of the dam.)