Arresto and “arrest” are often false friends, since in criminal procedure “arrest” is generally rendered in Spanish as detención, and “to arrest” or “to make an arrest” is detener: “the suspect was arrested” (se detuvo al sospechoso). In that regard “arrest warrant” is orden de detención or, perhaps more accurately for Spain, auto de detención (since judges issue arrest warrants in the form of an auto). A person who is “under arrest” (que está detenido) is often known (particularly in AmE) as an “arrestee” (el detenido) and will have an “arrest record” (ficha policial or antecedentes policiales). In that regard, the expression “arrestee rights” (known in the US as “Miranda rights”) denotes los derechos del detenido and include the “right to remain silent” (el derecho de guardar silencio), the “privilege against self-incrimination” (derecho a no declarar contra sí mismo y a no confesarse culpable) and the “right to counsel” (el derecho a la asistencia letrada).

In contrast, in Spain arresto is most often used in military law contexts to denote the arrest of military personnel (arresto en prisión militar), but there are several exceptions. Arresto sustitutorio (por impago de multa) describes a custodial sentence (pena privativa de libertad) to be served for failure to pay a fine imposed as the result of a criminal conviction. And arresto was likewise previously used in expressions such as arresto domiciliario (“house arrest”) and arresto de fin de semana (“weekend arrest”), two former custodial sentences that under the present Spanish Criminal Code are known as pena de localización permanente and generally require the offender to wear some type of electronic monitoring device such as an ankle monitor, known in Spain as a pulsera (or) tobillera telemática.

As for “detention,” the term is used in the common expression “arrest and pretrial detention.” Here “arrest” denotes detención, while “pretrial detention” (also called “pretrial custody”) refers to prisión provisional (or) preventiva. Thus, “arrest and pretrial detention” may be rendered as detención y prisión provisional (or) preventiva. And, in other respects, the Spanish criminal law offense of detención ilegal is akin to the concept of “false imprisonment” of Anglo-American jurisdictions.