Adhesión and “adhesion” may be cognates in an expression such as “adhesion contract” (contrato de adhesión). But in the sense of adhesión a un tratado, adhesión is more appropriately rendered as “accession,” as in acuerdo de adhesión (“accession agreement”) or la adhesión de España a la CEE (“Spain’s accession to the EEC”). In this case the appropriate verbs are adherir and “accede:” Estados miembros que se han adherido a la Unión Europea (“Member States that have acceded to the European Union”).

In other respects, in the language of court decisions adherirse is used to denote a judge’s “joining” another’s opinion: adherirse al voto particular disidente/discrepante o concurrente (“to join a dissenting or concurring opinion”). Thus, for example, voto particular concurrente que formula el Magistrado don Luis López Guerra y al que se adhiere el Magistrado don Tomás S. Vives Antón refers to a “concurring opinion filed by Judge Luis López Guerra in which Judge Tomás S. Vives Antón joined.” Likewise, in English an expression such as “Justice White, with whom Justice Blackmun and Justice Stevens join, dissenting” denotes a voto particular disidente (or) discrepante formulado por el Magistrado White, al que se adhieren los Magistrados Blackmun y Stevens.

In an additional context, in Spain’s former Civil Procedure Act (Ley de Enjuiciamiento Civil de 1881) the successful party to a lawsuit could join the losing party’s appeal (called adherirse a la apelación) to challenge some aspect of the judgment being contested. In the present Civil Procedure Act (Ley 1/2000) adhesión a la apelación has been replaced by the concept of impugnación del recurso. In that regard, once the appellant (apelante) has filed his appeal, the appellee or respondent (apelado) may file a brief opposing the appeal (escrito de oposición al recurso) or, if warranted, a brief challenging specific aspects of the appeal that he deems prejudicial to his interests (escrito de impugnación de la resolución apelada en lo que le resulte desfavorable).