A panel investigating mass surveillance with regard to its legal status has found that the programs operated by the "5-eyes" nations violate international laws to which they are all signatories to. The International Covenant on Civil and Political Rights is a document that the US signed in 1992 that in section 17, obligated the US to respect the privacy rights of individuals. The specific language used is pretty clear in its purpose, and it is pretty clear that the 5-eyes programs are in violation of these exact terms.
The provision reads:
"That individuals have the right to share information and ideas with one another without interference by the State, secure in the knowledge that their communication will reach and be read by the intended recipients alone.”
The report asserts that current programs are a violation:
“Bulk access technology is indiscriminately corrosive of online privacy and impinges on the very essence of the right guaranteed by article 17. In the absence of a formal derogation from States’ obligations under the Covenant, these programs pose a direct and ongoing challenge to an established norm of international law.”
It also asserts that the number one defense that the US uses for justification of its mass surveillance programs (that it exempts Americans from suspicionless surveillance) is in and of itself another violation of international law:
The Special Rapporteur concurs with the High Commissioner for Human Rights that where States penetrate infrastructure located outside their territorial jurisdiction, they remain bound by their obligations under the Covenant. Moreover, article 26 of the Covenant prohibits discrimination on grounds of, inter alia, nationality and citizenship. The Special Rapporteur thus considers that States are legally obliged to afford the same privacy protection for nationals and non-nationals and for those within and outside their jurisdiction. Asymmetrical privacy protection regimes are a clear violation of the requirements of the Covenant.
The full document submitted to the UN can be read here: