The peculiar term unipersonal is frequently used in Spain in at least two different legal contexts. With respect to the Spanish court system, a distinction is made between juzgados that have only one sitting judge (called jueces), and tribunales on which several judges (magistrados) sit in panels of (usually) three judges. Where warranted, to underscore this distinction juzgados having only one sitting judge are often described as órganos unipersonales, while tribunales on which judges sit in panels are called órganos colegiados. The often-repeated literal translations of these expressions as “unipersonal courts” and “collegiate courts” would likely be more appropriately rendered respectively as “single-judge courts” and “multi-judge courts” (or) “courts in which judges sit in panels.”

In other respects, in the context of corporate law unipersonal is used to describe companies with a single member or shareholder. Thus, a Sociedad de Responsabilidad Limitada Unipersonal (abbreviated S.R.L.U. and more often known simply as a Sociedad Limitada Unipersonal, or S.L.U.) may be described as a “single-member limited liability company,” while a Sociedad Anónima Unipersonal (S.A.U.) is a “single-shareholder corporation.” (In that regard, owners of Spanish limited liability companies are perhaps more appropriately described as “members” rather than “shareholders,” since by law owner interests in S.L.’s cannot be called “shares” [acciones], but rather are known as participaciones.)

Perhaps it should be underscored that in business law contexts unipersonal may be used with very different meanings in Spain and in Spanish-American jurisdictions. As indicated above, in Spain unipersonal designates a single-shareholder corporation (sociedad anónima unipersonal) or a single-member limited liability company (sociedad de responsabilidad limitada unipersonal). But, for example, in Chile and Uruguay unipersonal is used in the expressions empresa unipersonal (and empresario unipersonal) to denote a business entity similar to what in the US is known as a “sole proprietorship” (and  its owner, the “sole proprietor” or “sole trader” in England and Wales). In  contrast, in Spain a “sole proprietor” is known as an empresario individual or comerciante individual.