Brazilian authorities have twice blocked access to WhatsApp, infuriating millions of app users. The issue illustrates the ongoing tension between the desire to protect personal privacy and also to pursue criminals.

Naturally, this concerns governments and security agencies. They know that access to messaging can help them fight crime. But if they demand access, they erode privacy; if they don’t, they may let criminals evade capture.

It’s fair to say, the world is still struggling to resolve the problem. Not least in Brazil, where lawmakers have twice blocked access to WhatsApp – and twice removed the block.

The actions have caused huge unrest. Brazilians love the service they call ZapZap. According to recent research, an estimated 96.2 per cent of Brazilians use it every day. Moreover, even the government is a user: Rio’s city hall has a WhatsApp channel for answering questions about construction work ahead of the 2016 Summer Olympics.

The first flashpoint between the Brazilian courts and WhatsApp’s owner Facebook came in December 2015 when Facebook refused to comply with a criminal investigation. A higher court overturned the order, and the service was only down for 13 hours.

The ‘peace’ was short-lived. In March the authorities arrested Facebook executive Diego Dzodan after he refused to comply with a court order to hand over messages sent by drug-traffickers.

Dzodan spent a day in jail. After he was released, he made it clear that Facebook couldn’t release the information even if it wanted to. “The way that information is encrypted from one cellphone to another, there is no information stored that could be handed over to authorities,” he said.

Diego Dzodan, Vice President Latin America at Facebook and Instagram

Here is the new twist in the story. The Snowden revelations increased public awareness of privacy and as a result apps like SnapChat (which auto-deletes messages) rose in popularity. In time, more messaging app providers moved to encrypt traffic too.

WhatsApp was one. It incorporated end-to-end encryption and better security features into its product. As a result, only users themselves can access the unencrypted messages.

Naturally, this has increased the risk of confrontation with law-makers. So it was that, weeks after the Dzodan arrest, the same judge – Marcel Maia Montalvão – ordered MNOs to block WhatsApp access again.

There has been some sympathy in Brazil for Montalvão, who has an admirable record for pursuing criminality. But millions of Brazilians depend on WhatsApp so his actions were bound to cause unrest.

This time, even Facebook CEO Mark Zuckerberg participated in the conflict. He posted a blog which urged direct action against the government.

He said: “The idea that everyone in Brazil can be denied the freedom to communicate the way they want is very scary in a democracy…Tomorrow, the Internet Freedom Caucus is hosting an event and will be introducing laws to prevent blocking internet services like WhatsApp…The greatest impact you can have is to show up in front of Congress at 6pm. There will be a lively discussion of the importance of connecting people…I hope you make your voice heard now and demand change.”

The actions taken against WhatsApp have been taken by individual judges pursuing their own criminal cases. However, there is now a move by government to formalise state access to internet communications.

This is a little surprising as Brazil was widely considered to have a ‘good’ record on user privacy.In 2014, it passed the Marco Civil ‘bill of rights’ framework for the Internet, affirming that users had the right to communicate privately and securely online.

Now, law makers are considering an about-turn. They are currently studying the recommendations of a Parliamentary Commission of Inquiry on Cybercrimes – called CPICiber – which is proposing more access for security forces.

The proposals worry many people. Even Tim Berners-Lee, inventor of the World Wide Web, has urged the government to reconsider. However, with the local media understandably focused on the possible impeachment of the Brazilian president, the story has received less coverage than expected.

Meanwhile, Brazilians have responded by investigating alternatives to WhatsApp. Reports say the bans handed Telegram more than seven million new users in the first four months of 2016. 18 per cent of smartphone users in Brazil now use Telegram monthly.