This month the Swiss Federal Data Protection and Information Commissioner concluded that the Swiss-U.S. Privacy Shield as not providing an adequate level of protection under the Switzerland's Federal Act on Data Protection (FADP). See the policy paper posted here.
"The FDPIC considers that this lack of transparency and the resulting absence of guarantees concerning the interference of US authorities with privacy and informational self-determination of persons concerned in Switzerland is irreconcilable with: . . . the principles of the lawful processing of personal data."
United States laws on data surveillance may impact of the privacy of Swiss citizens' data in way does not honor the protections of the FADP. It will ultimately be up to Swiss courts to invalidate the privacy shield.