LONDON — In Spain, activists were convicted for social media posts that violated an expanded antiterrorism law. The Twitter accounts of German citizens were blocked because of rules enacted last year that prohibit hate speech. And a Dutch court determined Google must remove search results about a doctor punished for poor performance, in compliance with a privacy law.

Heralded as the world’s toughest watchdog of Silicon Valley technology giants, Europe has clamped down on violent content, hate speech and misinformation online through a thicket of new laws and regulations over the past five years. Now there are questions about whether the region is going too far, with the rules leading to accusations of censorship and potentially providing cover to some governments to stifle dissent.

The unintended consequences may be compounded as European governments pursue more laws and policies to restrict what communication can be shared online. Last month, Britain proposed appointing an internet regulator who would be empowered to block websites it considers harmful. The European Union is separately debating a law that would require tech companies to quickly remove terrorist-related content online.

With the growing body of European legislation, “there will be a lower standard for protection of freedom of expression,” said David Kaye, a University of California, Irvine, law professor whom the United Nations appointed to spotlight government efforts to restrict free speech. He added that Europe’s rules erode what had been a shared belief among the United States and other Western democracies to avoid censoring social media posts, YouTube videos, discussion forums and other internet content.