Duhaime's Law Dictionary

And/Or Definition:

Any combination of two options; one, the other (either), or both.

In law, it is synonymous with "or" which is taken to mean the same thing, and which is a preferred term for the concept of "either or both", which and/or attempts to convey.

 "And/or" is considered poor legal drafting and has been much criticized by the courts.

It is to the law as the square root of 2 is to mathematicians, an "irrational" word.

and/orIt has been called a "pestilent" and a "monstrous linguistic abomination".

"'And/or', that befuddling, nameless thing. That Janus-faced verbal monstrosity, neither word nor phrase, the child of a brain of some one too lazy or too dull to express his precise meaning, or too dull to know what he did mean."

One testator actually use the expression in a will. it is described as follows in Millon's article:

"Bequest to C, G, and Ph as tenants in common, but if any predecease T and leave issue surviving T, such issue to take the share 'their mother and/or father would have taken'.

"C and G were husband and wife, having no legitimate issue.

"But C having illegitimate issue.

"The Court held the and/or to include the latter."


  • Brown v Guaranty Estates Corp., 239 NC 295 (1954)
  • Millon, Elmer, Humor In Or Of Wills, 11 Vand. L. Rev. 737 (1957-1958), page 746 citing 21 Aust. L. J. 153 (1947)

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