Definition of "but for"

I once did lend my body for his wealth, Which, but for him that had your husband's ring, Had quite miscarried: […]

c. 1596–1598 (date written), William Shakespeare, “The Merchant of Venice”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act V, scene i]

She had a woman to take care of her called Mrs Poole — an able woman in her line, and very trustworthy, but for one fault — a fault common to a deal of them nurses and matrons — she kept a bottle of gin by her, and now and then took a drop over-much.

1847 October 16, Currer Bell [pseudonym; Charlotte Brontë], Jane Eyre. An Autobiography. […], volumes (please specify |volume=I to III), London: Smith, Elder, and Co., […]

But for that beneficent drug, not one of those men would have slept a moment during that fearful night.

1880, Mark Twain, A Tramp Abroad

In the whole extent of the house, which but for the old woman remained otherwise empty, Mr. Hyde had only used a couple of rooms

1886 January 5, Robert Louis Stevenson, Strange Case of Dr Jekyll and Mr Hyde, London: Longmans, Green, and Co.

In reconditioning existing locomotives, carriages and wagons, it is intended to replace obsolete types which would have been scrapped but for the war and to embody the latest scientific improvements.

1945 March and April, “Higher speeds”, in Railway Magazine, page 67

But for the stinging cold of January, this Casanova would not have taken shelter behind the coffeehouse window, […] .

1992, Najīb Maḥfūẓ, Sugar Street, page 48

This relevance can in many cases, as here, be tested by the sine qua non or ‘but for’ rule.

1985, Herbert Lionel Adolphus Hart, Tony Honoré, Causation in the Law, page xlv

When the expert constructs the "but for" world, he or she must construct it by taking into account how the plaintiff could have adjusted or did adjust to the changed circumstances.

2003, Mark A. Glick, Lara A. Reymann, Richard Hoffman, Intellectual Property Damages: Guidelines and Analysis, Wiley, page 37

But it is important to realise that but for causation is no more than indicative of true legal causation.

2003, A. P. Simester, G. R. Sullivan, Criminal Law: Theory and Doctrine, page 71

But in important ways the ‘but for’ test obscures the true role played by causal principles in assessing legal responsibility.

2006, Tal Becker, Terrorism and the State: Rethinking the Rules of State Responsibility, page 291