WhatsApp is suing the Indian government over new regulations in India that could allow authorities to make people’s private messages “traceable,” and conduct mass surveillance.

The Facebook-owned instant messaging service, which identifies India as its biggest market, said it filed the lawsuit in the High Court of Delhi on Wednesday. It said New Delhi’s “traceability” requirement, unveiled in February this year, violated citizens’ constitutional right to privacy.

“Civil society and technical experts around the world have consistently argued that a requirement to ‘trace’ private messages would break end-to-end encryption and lead to real abuse. WhatsApp is committed to protecting the privacy of people’s personal messages and we will continue to do all we can within the laws of India to do so,” WhatsApp said.

India first proposed WhatsApp to make software changes to make the originator of a message traceable in 2018. But its suggestion didn’t become the law until this year. Wednesday is the deadline for firms, including Facebook, to comply with India’s new IT rules.

WhatsApp’s move on Wednesday has come as a surprise and is highly unusual. Facebook has engaged closely with New Delhi over the years — to a point where allegations were made that it didn’t take action on some politicians’ objectionable posts because it feared it would hurt its business in India, the world’s second largest internet market.

“We have never seen a company sue the Indian government for asking for information.” said Jayanth Kolla, chief analyst at consultancy firm Convergence Catalyst. “We have seen companies push back, but they have never explored legal options in the past.”

WhatsApp itself is fighting a legal case in India currently, in the same aforementioned court, over its new privacy policy as New Delhi tries to get the Facebook-owned firm to withdraw the new terms.

Last year India banned over 200 Chinese apps, including TikTok, which at the time of blocking identified India as its biggest overseas market. India said it was banning the apps because they posed threat to national security and defence of India.

None of the Chinese firms sued the Indian government, with at least two telling TechCrunch on the condition of anonymity that it’s nearly impossible to win a court case in India when the national security issue has been raised. “So much so, that you are going to have a hard time even finding a lawyer who represents you,” an Indian official had told TechCrunch earlier.

India’s IT minister Ravi Shankar Prasad cited similar national concerns as he unveiled the revised IT rules in February this year.

This is a developing story. More to follow…