Google Tried to Change China. China May End Up Changing Google.

“I think that in the long term, they are going to have to open,” Mr. Brin told The Times.

Since then, China’s rules have only hardened, while a host of other governments have stepped up efforts to police speech online.

Now even many democratic governments are adopting stringent curbs on online speech. For instance, in Europe, a “right to be forgotten” rule has forced Google and other search engines to remove results that are judged to invade people’s privacy, and more rules governing hate speech and propaganda are in the works. Meanwhile, Edward Snowden’s leaks showed that the American and British governments have also hacked large internet companies, including Google.

“This argument makes me very sad: The world is becoming more like China, so therefore we might as well be in China,” said Rebecca MacKinnon, an internet freedom advocate at New America, a think tank.

She said that advocates of free speech and human rights had long found Google to be an ally in their efforts, and that a reversal in China would be regarded as a major defeat.

“I wrote a book where I warned that China is Exhibit A for how authoritarian governments adapt to the internet and then begin to change the internet,” Ms. MacKinnon said. “And if companies like Google are now throwing in the towel and saying, ‘Well, that’s where the internet is going’ and ‘If you can’t beat ’em, join ’em’ — well, that’s deeply troubling.”

If Google does go back to China, it will likely have to agree to an even more restrictive censorship regime than what it tolerated previously. Mr. Pichai has vowed to be transparent about how such a plan might roll out. But advocates said transparency alone would not mitigate their worries about Google’s shift.

“If Google is trying to promote openness and free societies, then transparency is going to be an insufficient way to make this better,” said Mr. Wizner of the A.C.L.U. “The transparency would be aimed at the rest of the world. Google wouldn’t be telling Chinese people, ‘Here’s what you can’t see.’”