Privacy advocates have long been wary of companies processing consumers' biometric data, especially whenfacial recognitionis involved.
Several states,including Illinois, have enacted laws regulating the use of biometrics.
Lawmakers have also proposedfederal legislationbanning the use of facial recognition.
Andlawsuits have been brought against companiesfor violating biometric privacy laws.
Mastercard is testing its experimental biometric payment process starting this week at five supermarkets in Sao Paulo, Brazil.
Mastercard said future tests are being planned for Asia and the Middle East.
