A Wall Street Journal investigation challenges Google’s assertion that its search algorithms are autonomous and objective.

“Google’s algorithms are subject to regular tinkering from executives and engineers who are trying to deliver relevant search results, while also pleasing a wide variety of powerful interests and driving its parent company’s more than $30 billion in annual profit,” the Journal said.

Google has “increasingly re-engineered and interfered with search results to a far greater degree than the company and its executives have acknowledged,” the newspaper’s investigation concluded.

Google disputed the findings. “We do today what we have done all along, provide relevant results from the most reliable sources available,” said spokeswoman Lara Levin.

Google maintains blacklists to prevent certain sites from showing up in search results, the Journal said. The newspaper’s finding undercut one of Google’s major defenses against regulators concerned over the company’s “anti-competitive practices, political bias and online misinformation,” the story said.