After months of negotiation, Johannes Caspar, a German data protection official, forced Google to show him exactly what its Street View cars had been collecting from potentially millions of his fellow citizens. Snippets of e-mails, photographs, passwords, chat messages, postings on Web sites and social networks — all sorts of private Internet communications — were casually scooped up as the specially equipped cars photographed the world’s streets.

“It was one of the biggest violations of data protection laws that we had ever seen,” Mr. Caspar recently recalled about that long-sought viewing in late 2010. “We were very angry.”

Google might be one of the coolest and smartest companies of this or any era, but it also upsets a lot of people — competitors who argue it wields its tremendous weight unfairly, officials like Mr. Caspar who says it ignores local laws, privacy advocates who think it takes too much from its users. Just this week, European antitrust regulators gave the company an ultimatum to change its search business or face legal consequences. American regulators may not be far behind.

The high-stakes antitrust assault, which will play out this summer behind closed doors in Brussels, might be the beginning of a tough time for Google. A similar United States case in the 1990s heralded the comeuppance of Microsoft, the most fearsome tech company of its day.

But never count Google out. It is superb at getting out of trouble. Just ask Mr. Caspar or any of his counterparts around the world who tried to hold Google accountable for what one of them, the Australian communication minister Stephen Conroy, called “probably the single greatest breach in the history of privacy.” The secret Street View data collection led to inquiries in at least a dozen countries, including four in the United States alone. But Google has yet to give a complete explanation of why the data was collected and who at the company knew about it. No regulator in the United States has ever seen the information that Google’s cars gathered from American citizens.

The tale of how Google escaped a full accounting for Street View illustrates not only how technology companies have outstripped the regulators, but also their complicated relationship with their adoring customers.

Companies like Google, Amazon, Facebook and Apple supply new ways of communication, learning and entertainment, high-tech wizardry for the masses. They have custody of the raw material of hundreds of millions of lives — the intimate e-mails, the revealing photographs, searches for help or love or escape.

People willingly, at times eagerly, surrender this information. But there is a price: the loss of control, or even knowledge, of where that personal information is going and how it is being reshaped into an online identity that may resemble the real you or may not. Privacy laws and wiretapping statutes are of little guidance, because they have not kept pace with the lightning speed of technological progress.

Michael Copps, who last year ended a 10-year term as a commissioner of the Federal Communications Commission, said regulators were overwhelmed. “The industry has gotten more powerful, the technology has gotten more pervasive and it’s getting to the point where we can’t do too much about it,” he said.

Although Google thrives on information, it is closemouthed about itself, as the Street View episode shows. When German regulators forced the company to admit that the cars were sweeping up unencrypted Internet data from wireless networks, the company blamed a programming mistake where an engineer’s experimental software was accidentally included in Street View. It stressed that the data was never intended for any Google products.

The F.C.C. did not see it Google’s way, saying last month the engineer “intended to collect, store and review” the data “for possible use in other Google products.” It also said the engineer shared his software code and a “design document” with other members of the Street View team. The data collection may have been misguided, the agency said, but was not accidental.

Although the agency said it could find no violation of American law, it also said the inquiry was inconclusive, because the engineer cited his Fifth Amendment against self-incrimination. It tagged Google with a $25,000 fine for obstructing the investigation.

Google, which has repeatedly said it wants to put the episode behind it, declined to answer questions for this article.

“We don’t have much choice but to trust Google,” said Christian Sandvig, a researcher in communications technology and public policy at the University of Illinois. “We rely on them for everything.”

That reliance has built an impressive company — and a self-assurance that can be indistinguishable from arrogance. “Google doesn’t seem to think it ever will be held accountable,” Mr. Sandvig said. “And to date it hasn’t been.”

When Street View was introduced in 2007, it elicited immediate objections in Europe, where privacy laws are tough. The Nazis used government data to systematically pursue Jews and other unwanted groups. The East German secret police, the Stasi, similarly controlled data to monitor perceived enemies.

“In the United States, privacy is a consumer business,” said Jacob Kohnstamm, chairman of the Dutch Data Protection Authority. “In Europe, it is a fundamental rights issue.”

Germany was a hotbed of protest. In Molfsee, a town of 4,800 people on the Baltic Sea, the deputy mayor, Reinhold Harwart, organized a group of residents in a protest.

“The main feeling was: Who gives Google the right to do this?” Mr. Harwart, now 74, said in a recent interview. “We were outraged that Google would come in, invade our privacy and send the data back to America, where we had no idea what it would be used for.”

Google offered few clues. After French privacy regulators inspected a Street View car in early 2010, the company was forced to explain that the cars were collecting information about household’s Wi-Fi networks — in essence, how they connected to the Internet — to improve location-based services.

Peter Fleischer, Google’s global privacy counselor, wrote in a blog post on April 27, 2010, that the company had not previously revealed this part of Street View because, “We did not think it was necessary.” But he said only technical data about networks was being collected, not the actual content sent out.

Still, German regulators, particularly Mr. Caspar, the data protection commissioner for Hamburg, were alarmed. Google, Mr. Caspar noted, had said nothing about collecting Wi-Fi data when negotiating permission for Street View.

Mr. Caspar wanted to inspect a Street View car. Google first said it didn’t know where they were, so it couldn’t produce them. Then, on May 3, it allowed a technical expert in Mr. Caspar’s office to see a vehicle. But the hard drive with data was missing.

Faced with the Germans’ persistence, Google published a post, on May 14, 2010, saying it had been prompted to “re-examine everything we have been collecting.” It turned out that Google was collecting e-mails and other personal data after all.

For a company like Google, which thrives on data, more is always better.

“The Google privacy officers are going to look at this and say, ‘It’s not illegal, maybe no one is ever going to be the wiser, and meanwhile we’ll have stored the data away in some big database,’ ” said Helen Nissenbaum, a privacy expert at N.Y.U. “We’re so enthralled with data, and the good it can bring, that we might overlook any problems.”

Mr. Caspar asked to see the hard drive. Google said handing it over could expose it to liability for violating German telecommunications law, which prohibits network operators and other data managers from disclosing the private communications of their clients.

This made no sense to Mr. Caspar, who explained that as data protection commissioner he was empowered to receive the data. Finally, in autumn 2010, the company yielded and gave Mr. Caspar the hard drive. By this point, Hamburg prosecutors had opened a criminal investigation.

Google was equally resistant with the American authorities.

Richard Blumenthal, Connecticut’s attorney general at the time, announced in late June 2010 that he and attorneys general from more than 30 other states had begun an investigation. Like the Europeans, they asked for the data. For months.

“Google resisted providing more information, even in the face of its acknowledgment that the collection was a mistake,” Mr. Blumenthal recalled in a recent interview.

Google argued that its data scooping was legal in the United States. But it told regulators it could not show them the data it collected, because to do so might be breaking privacy and wiretapping laws.

In December 2010, Mr. Blumenthal issued a civil investigative demand — the equivalent of a subpoena — and threatened further legal action if he did not get results. Then he became Connecticut’s junior senator and his successor, George Jepsen, took over.

No formal settlement was ever reached.

Some of those who were involved in the case are mystified.

“I cannot think of a single other multistate case that just disappeared,” said one former state regulator who asked not to be named since he did not want to be seen as bashing his former colleagues. “Individual state investigations, yes. But to start up a multistate and not end it with at least a consent judgment or even some token resolution is very unusual.”

A spokeswoman for Mr. Jepsen said the inquiry was still “active and ongoing.” Mr. Jepsen declined to be interviewed.

“The legal platform has not kept pace with the technology platform,” Mr. Blumenthal said. “So the investigative effort was done with less legal ammunition than might otherwise exist.”

The same was true of other challenges to Street View.

Citizens in several states filed suits against Google, saying the company had violated federal wiretapping laws through Street View. These suits were consolidated into a class action in San Francisco.

Google moved for dismissal, arguing that because it had picked up information only from unencrypted networks, it had not broken the law. In a significant loss, a federal judge said what the company was doing might be more akin to tapping a phone and allowed the suit to proceed. But he let Google appeal immediately, saying these were novel questions of law. The case may eventually end up at the United States Supreme Court.

In Germany, Mr. Caspar’s effort has also ground to a stop. He is waiting for prosecutors to file the criminal charges. If they do not, he said he would file his own administrative charges.

As for the engineer at the center of the controversy, Marius Milner lives in Palo Alto, Calif., in the heart of Silicon Valley, and apparently still works for Google. His garage door was open, displaying a black Miata convertible with a license plate holder featuring the famous phrase from the Google search page, “I’m feeling lucky.”

During a brief conversation on his front porch, Mr. Milner declined to say much of anything.