UI
Unemployment Insurance

UIFSA
Uniform Interstate Family Support Act

UIFSA
The American uniform child and spousal support legislation, the Uniform Interstate Family Support Act already adopted and implemented by most states and expected to be law throughout the USA soon. It is the successor of URESA and is a long-arm statutes as it gives the state which issues the first support order jurisdiction over the support payor anywhere in the USA for the purposes of varying that order. For more information, please see http://wwlia.org/us-uifsa.htm

Ultra vires
Without authority. An act which is beyond the powers or authority of the person or organization which took it.
Uniform Interstate Family Support Act (UIFSA), and Uniform Reciprocal Enforcement of Support Act (URESA)
laws enacted at the State level which provide mechanisms for establishing and enforcing support obligations when the noncustodial parent lives in one State and the custodial parent and the children live in another

Unjust enrichment
A legal procedure whereby you can seek reimbursement from another who benefitted from your action or property without legal justification. There are said to be three conditions which must be met before you can get a court to force reimbursement based on "unjust enrichment": an actual enrichment or benefit to the defendant, a corresponding deprivation to the plaintiff, and the absence of a legal reason for the defendant's enrichment. For example (and only theoretically as many countries have laws which have modified equity law in some situations), if you found somebody else's cash and spent it, you might be sued for reimbursement under unjust enrichment. The legal theory behind unjust enrichment is the constructive trust, which the court imposes upon the circumstances to hold the person unjustly enriched as the trustee for the person who should properly get the property back, held to be the beneficiary of the constructive trust.

UPA
Unreimbursed Public Assistance

URESA
Uniform Reciprocal Enforcement of Support Act of the United States, as created in 1950 by the National Conference of Commissioners on Uniform State Laws. This was the first family support uniform legislation in the USA and it was ultimately adopted, in some form or another, by all the US states. It was updated in 1968 and the revised version became known as "RURESA", the initial "R" standing for "Revised." It has been replaced by UIFSA. For more information, please see http://wwlia.org/us-uifsa.htm

Usufruct
From ancient Roman law (and now a part of many civil law systems), "usufruct" means the rights to the product of another's property. For example, a farmer may give a right of "usufruct"of his land to a neighbor, thus enabling that neighbor to sow and reap the harvest of that land.

Usury
Excessive or illegal interest rate. Most countries now prohibit interest rates above a certain level; and rates which exceed these levels are called "usury".

Utility/Telecom Interconnection
a mechanism for resolving disputes that exists outside the state or federal judicial system specifically dealing with issues of communications at a distance (see also arbitration and mediation).