For the case of a German citizen or resident, or just someone who happens to be in Germany.

For the case of a Spanish citizen or resident, or someone who happens to be in Spain, Spain's justice trumps Germany's justice.

As it should be as long as there is not a federal European justice that trumps both.

The same is arguably true in the US. It would federal law to force states to recognise each other's arrest warrants and it is federal law enforcement that would force one state to hand over a person to another state. As well as there being a federal police force (the FBI) with the ability to carry out an arrest.

En un viejo país ineficiente, algo así como España entre dos guerras civiles, poseer una casa y poca hacienda y memoria ninguna. -- Gil de Biedma