Law enforcement authorities and technologists have argued over encryption controls for decades. On one side, privacy advocates and tech executives believe people should be able to have online communications free of snooping. On the other side, law enforcement and other authorities believe tough encryption makes it impossible to track child predators, terrorists and other criminals.

Mark Zuckerberg, Meta’s chief executive, has long positioned himself as a privacy champion. In 2019, he announced a plan to stitch together and encrypt all of his company’s messaging apps, a move that has taken years of technical infrastructure work. At the time, he acknowledged the risk it presented for “truly terrible things like child exploitation.”

Meta’s messaging services have recently been under particularly intense scrutiny in Europe, where the company has been fined billions of euros for violating data privacy laws. Lawmakers have also criticized Meta for not allowing its messaging services to easily work with other services like iMessage and Telegram, and has ordered the company to make it possible to send a message from Meta’s apps to competing apps.

Meta has recently reduced the number of its trust and safety employees who work on issues such as reducing misinformation and catching child predators, purveyors of exploitative material, or drug and arms traffickers.

End-to-end encryption gained more traction in 2013 after data leaked by the former National Security Agency contractor Edward J. Snowden appeared to show the extent to which the N.S.A. and other intelligence and law enforcement agencies were gaining access to users’ communications through companies like Yahoo, Microsoft, Google and Facebook without their knowledge.