set a precedent

set a precedent

To do something that establishes a standard, pattern, or policy that will be used in the future. The court's decision in this case will set a precedent that affects the lives of all citizens going forward. I'd rather that you don't let Tommy eat his dinner in front of the television—I don't want to set a bad precedent for mealtimes.
See also: set
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

set a precedent

to establish a pattern; to set a policy that must be followed in future cases. I'll do what you ask this time, but it doesn't set a precedent. We've already set a precedent in matters such as these.
See also: set
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

set a precedent

Establish a usage, tradition, or standard to be followed in the future. For example, He set a precedent by having the chaplain lead the academic procession. The word precedent here signifies a previous instance or legal decision upon which future instances are based, a usage dating from the early 1400s. In British and American law it more specifically refers to a legal decision that may be used as a standard in subsequent cases.
See also: set
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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References in periodicals archive ?
ISLAMABAD -- The federal government Tuesday set a precedent in the country's history when its cabinet members voluntarily decided ten per cent reduction in their salaries.
After all, if San Jose were able to force MLB's hand, then it would set a precedent for other clubs in the league to relocate.
Original jurisdiction: The Court must hear eases that may set a precedent (ruling that can later be used to justify a similar case), and other legal disputes that involve a state or the federal government.
It says it is out "to reclaim legal ground in this country for the body of Christ." Its leaders hope the decision against the University of Wisconsin will set a precedent for public schools around the country.
And yes, it will set a precedent for attacking minority rights in other provinces.
The first opportunity to set a precedent for UN involvement in a military conflict came with the Korean War.