Safe third country agreements are not explicitly mentioned in the 1951 Convention Relating to the Status of Refugees or the 1967 Protocol Relating to the Status of Refugees. Instead, their legality is derived from Article 31 of the 1951 convention, which states that a refugee should not be punished for illegally entering a country if they are arriving directly from a country where they were under threat. The Office of the United Nations High Commissioner for Refugees (UNHCR) itself has cautioned against interpreting safe third country agreements too broadly, though it acknowledges that they may be acceptable in some circumstances. Such ambiguities have led some legal professionals in Canada to question the legality of the Canada–United States Safe Third Country Agreement.