impracticability

1. The state or quality of being impracticable; infeasibility. Goldsmith.

2. An impracticable thing.

3. Intractableness; stubbornness.

Substantial difficulty or inconvenience in following a particular course of action, but not such insurmountability or hopelessness as to make performance impos- sible.

Rule 23 of the Federal Rules of Civil Procedure establishes impracticability as one of the grounds for permitting a class action in federal courts. "[T]he class is so numerous that joinder of all members is impracticable." In such a situation, the court will permit a few individuals who have made a motion to it to represent in one lawsuit a large number of persons who will be similarly affected by the legal outcome of the particular action. The group to be represented must be so large that there would be significant problems or impracticability in bringing each member before the court to appear as a party to the action. For purposes of certification as a class, the prospective representatives must show that joinder can be accomplished only with substantial difficulty, expense, and hardship, but not that such joinder cannot be done at all. State procedural rules also require that joinder of all prospective class members be impracticable before permitting the commencement of a class action in state courts.

In the law governing sales, the Uniform Commercial Code allows either party to a contract to be excused from the legal obligations created by it where performance becomes impracticable because an unexpected event has occurred, such as a severe shortage of supplies due to unexpected and continual flooding.

See: impossibility.

The noun has one meaning:

Meaning #1: the quality of not being usable
  Synonym: impracticableness
  Antonym: practicability (meaning #1)