Rather than “to manifest interest” as the term is sometimes rendered, in legal contexts interesar often has the meaning of solicitar (to request, to petition, to motion, etc.), especially when used in pleadings and other court documents. As defined in the DLE, “interesar may mean “solicitar o recabar de alguien, datos, noticias, resoluciones, etc.” Here are a few examples in which interesar denotes solicitar in the sense of “petitioning the court,” with possible English translations:
- práctica de la prueba que interesábamos en nuestro escrito de querella (examination of evidence requested in our criminal complaint)
- el Ministerio Fiscal interesó que se hiciera a los solicitantes audiencia (the prosecution moved that the applicants be granted a hearing)
- se interesaba que se señalara nuevo día y hora para la vista (a motion to continue was filed, requesting a change of date and time for the hearing)
- se presentó escrito por el que se interesaba el sobreseimiento de las actuaciones (a motion to dismiss was filed)
- el demandante interesaba una indemnization por daños (the plaintiff filed for damages)
Léxico Jurídico Español-Inglés 
Just for the record. In Mexico, we would never use the verb “interesar” in legal contexts along the lines you mentioned; it would be very confusing. Indeed, “solicitar” would be our choice of words. This is a good example of the difference in legal usage of Spanish terms between and among different Spanish-speaking countries.
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Hi, Javier,
Thanks for your comment. Obviously, although present in the DLE, this meaning of “interesar” may not be used in all Spanish-speaking jurisdictions. But since I have seen several instances in which US translators misunderstood this use of “interesar” when rendering Spanish legal texts, I thought it would be worth documenting in a blog entry.
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