Do you live in the land of and/or? Are you Andorian? (The clever name comes from David Elliott, The Orians, the Andians, and the Andorians, 50 Clarity 10, 11 (2004).)

Then it’s time to move. Every source on legal language that discusses and/or advises not to use it. Here’s a sampling:

“And/or is best discarded.” J.K. Aitken, Piesse’s The Elements of Drafting 85 (9th ed. 1995).

“With experience you’ll find that you don’t need and/or.” Bryan A. Garner, Legal Writing in Plain English 112 (2000).

“If the lawyers did invent and/or, they owe it to the common language to atone, by eliminating and/or from the legal vocabulary . . . .” David Mellinkoff, Legal Writing: Sense and Nonsense 56 (1982).

Judges have been even less kind. In fact, some of the harshest things ever said about legal language have been said about and/or.

“[T]he much condemned conjunctive-disjunctive crutch of sloppy thinkers . . . .” Raine v. Drasin, 621 S.W.2d 895, 905 (Ky. 1981).

“[An] abominable invention . . . as devoid of meaning as it is incapable of classification by the rules of grammar and syntax.” Am. Gen. Ins. Co. v. Webster, 118 S.W.2d 1082, 1084 (Tex. Civ. App.—Beaumont 1938, writ dism’d).

“[T]hat befuddling, nameless thing, that Janus-faced verbal monstrosity, neither word nor phrase, the child of a brain of someone too lazy or too dull to express his precise meaning . . . .” Employers’ Mut. Liab. Ins. Co. of Wis. v. Tollefsen, 263 N.W. 376, 377 (Wis. 1935).

Why all the vitriol and venom? After all, the phrase does have a reliable meaning. “A and/or B” means “A or B or both.” But there’s ambiguity hidden within the phrase, and not everyone uses the phrase appropriately. The problems with and/or arise from three sources.

First, and by itself can be ambiguous. “The bank may fund A and B.” If the bank chooses to fund A, must it also fund B? Or may the bank fund A but not B? It’s ambiguous, and litigation has ensued.

Second, or by itself can be ambiguous. “The bank may fund A or B.” If the bank chooses to fund A, is it prohibited from funding B? Or may the bank fund both A and B? It’s ambiguous.

To solve the problems created by the ambiguity of and and or, and/or might work, but given its bad reputation, a better approach is to avoid and/or and add clarifying words. See Kenneth A. Adams, A Manual of Style for Contract Drafting 198 (2d ed. 2008). For example:

The bank may fund A and B but not one or the other.
The bank may fund A or B or both.
The bank may fund A or B but not both.

Third, some writers use and/or where it’s inappropriate. For example, imagine a job application that says: “Check here if you cannot work nights and/or weekends.” If you check the box, what does it mean? You cannot work nights? You cannot work weekends? You cannot work either? It’s fatally ambiguous.

But you can’t fix it this way: “Check here if you cannot work nights or weekends or both.” That doesn’t help. You need two check boxes: “Check here if you cannot work nights. Check here if you cannot work weekends.”

Given the three sources of problems with and/or, here’s my advice: Avoid and/or, but don’t assume there’s always an easy fix by writing “A or B or both.” You have to think through the alternatives and be sure what you want to say.