What are Spain's laws regarding self defense? Does Spain have the equivalent of "Stand your ground," or "Duty to retreat?"
First, I am not a lawyer, but my answer could be a starting point.
On the surface, it seems that yes, in some form, stand your ground is permitted. At least comparing to the Wikipedia definition: "people may use deadly force when they reasonably believe it to be necessary to defend".
Per the Spanish Penal Code art. 20 (my translation to English follows):
Están exentos de responsabilidad criminal:
- El que obre en defensa de la persona o derechos propios o ajenos, siempre que concurran los requisitos siguientes:
Primero. Agresión ilegítima. En caso de defensa de los bienes se reputará agresión ilegítima el ataque a los mismos que constituya delito y los ponga en grave peligro de deterioro o pérdida inminentes. En caso de defensa de la morada o sus dependencias, se reputará agresión ilegítima la entrada indebida en aquélla o éstas.
Segundo. Necesidad racional del medio empleado para impedirla o repelerla.
Tercero. Falta de provocación suficiente por parte del defensor.
The following cases are exempt from criminal responsibility:
- He who acts in defense of himself, or in defense of his own rights, or of the rights of others, if all the following conditions are met:
First. Illegitimate aggression. In the case of the defense of property, the attack on said property will be considered illegitimate aggression if it is a crime and it puts the property in serious danger of imminent damage or destruction. In the case of defense of a dwelling*, an illegal entry into said dwelling will be considered illegitimate aggression.
Second. Rational (reasonable?) necessity of the means employed to prevent or repel the aggression.
Third. That the defender had not provoked the attacker sufficiently.
But in practice, there was a case where two thieves entered a house, beaten the wife, the husband shot first into the air, then he shot one of the thieves who later died. The stand-your-ground argument was considered only to give the husband lighter sentence, did not absolve him completely. The court reasoned that he could have shot into the air second time. This will hinge on the interpretation of the 2nd condition (rational necessity). I did not read the sentence itself, just the article, maybe later.
* - not sure what is meant by "dependencias", omitted in the translation, maybe surroundings, guess it is not that important