It's happening... for the fourth time. In a criminal court case, a judge ordered the retrieval of text messages sent on the Facebook-owned app, but because the messages are encrypted, the information could not be given to the Brazilian courts. In protest, the judge shut down WhatsApp communications within the country. Fortunately, the Brazilian Supreme Court struck down the ruling and service was eventually restored, but this is a reminder that social media and messaging apps can be shut down arbitrarily.

Source: https://techcrunch.com/2016/07/19/whatsapp-blocked-in-brazil-again/