Goodhart's law is an adage often stated as, "When a measure becomes a target, it ceases to be a good measure". It is named after British economist Charles Goodhart, who is credited with expressing the core idea of the adage in a 1975 article on monetary policy in the United Kingdom:Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes.

Charles Albert Eric Goodhart, is a British economist. He worked at the Bank of England on its public policy from 1968–1985, and worked at the London School of Economics from 1966–1968 and 1986–2002. Charles Goodhart's work focuses on central bank governance practices and monetary frameworks. He also conducted academic research into foreign exchange markets. He is best known for formulating Goodhart's Law, which states: "When a measure becomes a target, it ceases to be a good measure."