Yes, Swiss law provides strong protection for legal privilege for external lawyers (and to a more limited extent to in-house counsel; see section 3).

The legal privilege for external lawyers is based on the duty of confidentiality the agent owes to their principal under the law of mandates (cf. article 398 of the Swiss Code of Obligations) and embedded in the professional rules governing the conduct of attorneys admitted to practice in Switzerland, as codified in the Swiss Federal Act on Attorneys (FMLA). It is further reinforced by Swiss criminal law and given effect through several privileges to withhold information in procedural laws.

Specifically, article 13 of the FMLA requires attorneys admitted to practice in Switzerland to maintain confidentiality regarding all information entrusted to them by their clients.

Further, under article 321 of the Swiss Criminal Code, attorneys are obliged to keep secret any and all information that their clients admit to them and that they learn in connection with their mandate. A deliberate breach of this professional secrecy obligation is subject to a monetary penalty or a custodial sentence of up to three years.

Swiss procedural laws covering civil, criminal and administrative proceedings also protect legal privilege. For example, article 160 of the Swiss Code of Civil Procedure (CPC) or article 264 of the Swiss Criminal Procedure Code ("CrimPC") allow parties (and third parties) to refuse to produce correspondence with an attorney, provided it concerns the attorney's typical professional activity (i.e., legal advice and representation). On the same basis, both the attorney and the client may refuse to testify about such communications (cf. article 160 of the CPC and article 171 of the CrimPC).