vested interest

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Law A right or title, as to present or future possession of an estate, that can be conveyed to another.
• noun A fixed right granted to an employee under a pension plan.
• noun A special interest in protecting or promoting that which is to one's own personal advantage.
• noun Those groups that seek to maintain or control an existing system or activity from which they derive private benefit.

from the GNU version of the Collaborative International Dictionary of English.

• a special personal interest, usually financial, in an existing system, law, or institution, which hinders a person from making objective decisions regarding that system, law, or institution. A vested interest may be one which benefits a relative, or, in an extended sense, one which defends a person's own reputation or previously expressed views.
• a right given to an employee by a pension plan, which cannot be taken away.
• the persons, corporations, or other groups which benefit most (usually financially) from the existing system of institutions, laws, and customs.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun law a right or title that can be conveyed
• noun a fixed right granted to an employee, especially under a pension plan
• noun a stake, often financial, in a particular outcome
• noun a group of people or organizations with such a stake
• noun an exceptionally strong interest in protecting or promoting something to one's own advantage

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (law) an interest in which there is a fixed right to present or future enjoyment and that can be conveyed to another
• noun groups that seek to control a social system or activity from which they derive private benefit