There are multiple definitions - click on the translation that matches your context.
legal opinion means:
Substantiv
partial
noun
Since a "legal opinion" can mean both a general legal "view" on a given issue or topic and also a formal written statement issued to a client memorializing that view (with documented support), we would suggest translating Rechtsauffassung as "legal view", which more accurately describes the nature of that German word. A Rechtsgutachten is a formal written legal opinion.
written legal advice on a point of law given by a lawyer to his or her client
The client asked that his attorney draft a legal opinion regarding his chances of winning his case.
written statement by a judge, group of judges, court or legal expert concerning the legal reasoning that led to a certain judgment, ruling or decision
Justices have each to reach their own conclusions and then write their legal opinion.