used euphemistically to describe a person or statement that lies or deliberately withholds information
The phrase economy of truth was used in the 18th century by the orator Edmund Burke (1729-97), while in the 19th century Mark Twain observed Truth is the most valuable thing we have. Let us economize (Following the Equator - 1897). The present phrase became current after its use in the Spy catcher trial in the New South Wales Supreme Court : Robert Armstrong, head of the British Civil Service, was reported as saying of a letter : It contains a misleading impression, not a lie. It was being economical with the truth.
2003 - Observer - He is ruthless in pursuit of commercial goals, otherwise he would not have been so economical with the truth two months ago when he ruled out any notion of signing Beckham.