Duhaime's Law Dictionary

Horizontal Agreement Definition:

An agreement between two or more marketplace competitors which resolves some avenue of rivalry between them.

Related Terms: Per Se Doctrine

Areeda and Hovenkamp write:

"An arrangement is said to be horizontal when its participants are either actual or potential rivals at the time the agreement is made; and the agreement eliminates some avenue of rivalry between them."

Because of the obvious exigency of corporate priorities in regards to market-share, virtually any agreement between competitors could be construed as anti-competitive. Indeed, historically, the American antitrust per se doctrine was built around the suspicion arising from horizontal agreement.

But not all agreements between competitors, horizontal agreements, are illegal or in violation of the applicable competition or antitrust statute per se but many are, most notably price fixing or organized boycotting.


  • Areeda, P. and Hovenkamp, H., Fundamentals of Antitrust Law, 3rd Ed. (New York: Wolters Kluwer, 2009), pages 19-4 to 19-5.

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