I believe there is a typo here: the term is "prejudicialidad" (not "perjudicialidad") and when "cuestiones prejudiciales" (pretrial issues) arise in a proceeding, they must be resolved before the matter at hand can be tried.

This is explained in detail here:
https://guiasjuridicas.wolterskluwer.es/Content/Documento.as...


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Note added at 1 hr (2019-11-08 22:39:08 GMT)
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Here is a simple definition:

"cuestiones que se plantean en un proceso que deben ser resueltas con anterioridad de la sentencia, ya que condicionan el resultado del proceso"

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Note added at 1 hr (2019-11-08 22:54:10 GMT)
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Here is the definition of "cuestión prejudicial civil" from the Diccionario de Español Jurídico:

"cuestión prejudicial que se produce cuando para resolver el objeto del litigio es necesario resolver sobre alguna cuestión que constituye el objeto de otro litigio ante el mismo o distinto tribunal civil. A petición de las partes podrá suspenderse el proceso hasta que finalice el proceso civil que tenga la cuestión prejudicial.
https://dej.rae.es/lema/cuestión-prejudicial-civil



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Note added at 20 hrs (2019-11-09 17:21:12 GMT)
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A few final comments: the definitions offered above indicate that “prejudicialidad” is unrelated to either civil liability or collateral estoppel. As Adrian notes, collateral estoppel prohibits relitigating the same matter. “Prejudicialidad” involves two matters, neither of which has yet been litigated or adjudicated for the first time; so there is no “relitigation” implied. That is precisely the meaning of “prejudicial” in legal Spanish: “pre-trial” (or) “pre-judgment”. Indeed, the Diccionario de la Lengua Española defines “prejudicial” as “que requiere o pide decisión anterior y previa a la sentencia de lo principal.”

Just as an example, the expression “planteamiento de la cuestión prejudicial comunitaria” denotes a domestic court’s referral of a matter to the European Court of Justice for a preliminary ruling when the domestic court of an EU member state suspects that applying national law in his ruling on that matter may violate EU legislation. “Prejudicial” is also used in this sense in expressions such as “acuerdo (or) arreglo prejudicial” to denote a “pretrial (or) prejudgment settlement” between the parties to a conflict.

Thus, as the definitions posted above show, “prejudicialidad civil” involves suspending a pending matter until a decision on a second but related matter is adjudicated, when the judge considers that the outcome of the latter is essential for determining the outcome of the former.