A recent India Supreme Court ruling on privacy rights needs to be carefully followed by U.S. tech firms and those doing business in India.

The decision comes from a case over the Indian government’s use of the Aadhaar, a 12-digit identity number issued to all residents of India. Aadhaar, which is the world’s largest biometric ID system, can be used for such things as government benefits, tax collection, or the monitoring of financial transactions.