I would say it depends:
Questions that cannot be answered on German SE
Everything on the subsumption level, e.g.:
- Is a tree line a Befriedung in terms of § 123 Abs. 1 StGB?
That would be an innate legal discussion.
Questions that should be asked and answered on German SE
Questions on definitions (especially termini technici) should be okay regarding the legal context just like for any other specialization, however. Indeed, one might say that these belong to the juridicial scope as well, but equally one can hold that jurisprudence uses linguistic means here! As jonathan.scholbach put it: "Any legal discussion is ultimately a question about the semantics of the law text." Hence, legal definitions take place in the realm of semantics; and where could questions about semantics of a German (law) text be answered if not here?
On the other hand, obviously, such an answer must show the interaction between the original semantics of an phrase and its legal alternation. In the case of befriedetes Besitztum, that would include a depiction of the general meaning at the time the law was made (this is basically a question of linguistical change) and how the term is understood in the legal context today (which is plain semantics). In order to do so, it is not necessary to be a legal professional, but it is important to be aware of how such technical terms are handled in the legal context—they have one specific meaning that is assumed to be known.
An example for such a technical term: Diebstahl is legally defined (§ 242 Abs. 1 StGB) as:
eine fremde bewegliche Sache einem anderen in der Absicht [wegzunehmen], die Sache sich oder einem Dritten rechtswidrig zuzueignen […]
If we look up zueignen in DWDS, we find:
- (Jura) sich widerrechtlich etw. aneignen, etw. widerrechtlich in seinen Besitz nehmen
But despite the tag (Jura), this is not what zueignen means in § 242 Abs. 1 StGB! In the legal context, Zueignung = Enteignung + Aneignung. That means taking something into one's posession (in Besitz nehmen) and acting like its owner (Aneignung), while planning to give it back, is no (!) Zueignung and hence no Diebstahl, despite it satisfies the DWDS definition.
Thus, a hypothetical question like What does Zueignung mean? is indeed a question of semantics; but due to incompleteness, a dictionary like DWDS wouldn't be the right source. But that DWDS doesn't give the right answer does not in turn mean the question is not about semantics! It's just about specific semantics, but not unlike other questions about technical terminology, no matter if physics or art.
If dictionaries like DWDS, Duden etc. doesn't suffice in regard of the technical meaning, what sources can be used then? Again, one doesn't need to be a lawyer and turn to scientific literature since there are multiple reliable, yet easily accesible sources that reproduce legal sources like commentaries and case law. I would like to turn to the original question about befriedetes Besitztum again and give some sources as an example:
- First, one can look up when the term entered the law. That is nothing else than looking up when a novel or a newspaper article in question was published. In case of § 123 StGB, it has been there since the very first version of 1871/1872. With that knowledge, contemporary dictionaries (here the DWB) can be consulted. These enable to give correctly give the baseline meaning at that time.
- Also Wikipedia could help to get an overview and maybe links to authorative sources. In the article about Hausfriedensbruch, one would find a first hint: "Befriedete Besitztümer sind Bereiche, die in äußerlich erkennbarer Weise durch Umgrenzungen gegen willkürliches Betreten gesichert sind." This should be treated like first evidence for this term's meaning in the legal context. Then the references can be checked or other sources like judgements can be searched for more reliable evidence.
- Since the asker asked for English synonyms, one could refer to the English translation published by the German Ministry of Justice. This particular translation, e.g., was produced by a German professor of (comparative) criminal law at an English university and former judge at a German court. Hence, this translation is scientifically founded by a scientist who personally knows the German legal system, the English language and the differences between national law systems very well, and precisely for that reason such a source is reliable enough without previous knowledge.
Semantics remains semantics and semantics is on-topic on this site, even if it is the result of legal discussions. However, it is important to be aware of the existence of technical terms (in general, not only in law) and to account for them by referencing applicable sources instead of taking any general dictionary definition for granted despite it conflicts with the legal meaning. To do so, however, one doesn't need to be a lawyer, since the required legal information can be found in general reference works or on other sites designated for the general public.