An ultrahazardous activity in the common law of torts is one that is so inherently dangerous that a person engaged in such an activity can be held strictly liable for injuries caused to another person, even if the person engaged in the activity took every reasonable precaution to prevent others from being injured. In the Restatement of the Law 2nd, Torts 2nd, the term has been abandoned in favor of the phrase "inherently dangerous activity."

Categories of ultrahazardous activity.

Several categories of activities are commonly recognized as being inherently hazardous; those who engage in them are subject to strict liability. These include:

Transportation, storage, and use of dynamite and other explosives.

Transportation, storage, and use of radioactive materials.

Transportation, storage, and use of certain hazardous chemicals

Keeping of wild animals (for example animals that are not normally domesticated in that area).

Note that in this context, "domesticated" does not merely refer to animals that are commonly bred and raised in captivity, such as alligators.

Keeping of domesticated animals that have a known propensity for dangerous behavior (for example keeping a dog that has attacked people before).

Someone who is injured by one of these inherently hazardous activities while trespassing on the property of the person engaged in the activity is barred from suing under a strict liability theory. Instead, they must prove that the property owner was negligent.

In the United Kingdom, this area of law is governed by the rule established in Rylands v Fletcher.

Deep pocket as a slang term.

The term “deep pockets” (also given as “deep pocket” and “deep pocketed") is attested sparsely in the 1940s through the 1960s but became popular with the litigation explosion of the 1970s.

A person with “short arms and deep pockets” is a person (sometimes derided as “miserly” or “cheap") who saves money and doesn’t often spend it. The term “short arms and deep/long pockets” is cited in print from at least 1952.

In Ireland, this phrase was attached to a wealthy businessman from Tipparary who, upon his round of drinks, would break his glass on the floor, knowing the owner of the pub would ask him to leave. This was also called the “O’Shea Fiddle”.

A writ of execution (also known as an execution) is a court order granted to put in force a judgment of possession obtained by a plaintiff from a court. When issuing a writ of execution, a court typically will order a sheriff or other similar official to take possession of property owned by a judgment debtor. Such property will often then be sold in a sheriff's sale and the proceeds remunerated to the plaintiff in partial or full satisfaction of the judgment. It is generally considered preferable for the sheriff simply to take possession of money from the defendant's bank account. If the judgment debtor owns real property, the judgment creditor can record the execution to "freeze" the title until the execution is satisfied.