The usage of Aadhaar dropped to the lowest level in a year in June, declining over 40% from a record 1.48 billion authentications done using the unique identity number last September.Aadhaar was used 859 million times for authentication purposes in June, according to the Unique Identification Authority of India ( UIDAI ), the agency that administers the programme.The low was reached barely three months after the Supreme Court extended the deadline for linking Aadhaar with various services and facilities, including verification of bank and mobile phone customers, until it delivers the final judgement on its validity and usage. The court, which resumes after the summer break on Monday, is expected to rule on the matter soon.After the court reserved its verdict on May 10, the government extended the deadline to link permanent account numbers ( PAN ) with Aadhaar to March 31 next year, while the time limit to link Aadhaar to get subsidised rations has been pushed by three months to September 30.Aadhaar-based authentications have declined every month since September, except in March, when they rose to 1.125 billion from 996 million in February, according to the UIDAI website.After touching a peak of 1.48 billion in September, Aadhaar authentications fell to 1.46 billion in October. Last July, 966 million Aadhaar authentications were done and the figure crossed 1billion last August.An authentication is recorded when a citizen uses Aadhaar to avail of a service or links it to an existing service by providing the identity number, submitting biometrics ( fingerprints eye scan ) or using the one-time password (OTP) verification. More than 1.2 billion Aadhaar numbers have been generated so far.Demographic authentication — use of the Aadhaar number for verification — dropped to 170 m in June from 741.6 million last September. UIDAI chief operating officer AB Pandey did not comment on the declining trend of authentication.A senior government official, speaking on condition of anonymity, conceded that the non-mandatory requirement of Aadhaar for some services “was one of the factors” for the drop in authentications. “But one must also consider that there was a huge spike last September and October as the government was going full steam ahead with linking mobile phones and bank accounts with Aadhaar,” the official told ET.Almost 900 million bank accounts and 900 million mobile phones have been linked with Aadhaar after the government first set a deadline of March 31, 2018. “Saturation levels have been reached on Aadhaar linking and now the authentications are mainly regarding transactions being carried out by people to avail of welfare schemes and services,” the senior functionary said. “There is no reason to worry over the present authentication numbers… UIDAI will be raising its capacity to be able to carry out 3,000 million authentications every month.”Since January, the SC has been hearing the case related to the constitutional validity of Aadhaar and whether it can be made mandatory for PAN, mobile phone connections, passports, subsidised rations and bank accounts. In March, the apex court indefinitely extended the deadline for linking Aadhaar with various services and facilities. The court clarified in April that it had never directed the linking of mobile phones with Aadhaar and said the government had misinterpreted its 2017 order. A major issue before the SC is whether Aadhaar violates the right to privacy, which the court determined as fundamental in 2017.