Billion-dollar industries are built around the collection, compilation and protection of consumers’ personal data — from social-media platforms to e-commerce sites to data brokers.

While the federal government gears up for possible antitrust scrutiny on the data-driven business models of tech giants Facebook FB, +0.20% , Apple AAPL, +1.02% , Amazon AMZN, +0.66% and Google, there’s a twist: Many courts are still grappling with the basic question of whether someone’s data even has monetary value.

The Wall Street Journal reported that the Justice Department is preparing an antitrust investigation into Alphabet Inc.’s Google GOOG, +0.92% GOOGL, +0.95% . The House Judiciary Committee is launching a bipartisan investigation into a small number of “dominant and unregulated platforms,” the committee said in a statement on Monday.

Some 2.5 quintillion bytes of data are created every day. If 2.5 quintillion pennies would be laid out flat, they would cover Earth five times, MarketWatch previously reported. Most of the data is harvested, stored and owned by large companies.

When sites like Facebook and Instagram sell targeted advertising based on the aggregated user data they have access to — resulting in billions of dollars a year in revenue — users get nothing in return except the free use of the social-media platform.

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However, Facebook log-ins can be sold for as little as $5.20 each on the “dark web” because they afford criminals access to personal data that could potentially provide a gateway to other accounts.

The credentials to a PayPal PYPL, +0.31% account with a relatively high balance can be sold on the dark web for $247, on average, according to a report by content-marketing agency Fractl, which analyzed all the fraud-related listings on three large “dark web” marketplaces. A hacker’s fee for access to an account on a social media platform like Twitter TWTR, -4.83% could go for $129, according to Dell SecureWorks.

The value of data to companies and hackers provides insight into the contradictions on how much that data is actually worth.

The market is grappling with putting a price tag on your data, but the courts have yet to decide the value of that information. “It’s definitely up in the air,” said privacy-law expert William McGeveran, a professor of law at the University of Minnesota.

“ Consumers can only claim they were harmed by something like a data breach if they lost something of value — in other words, if their data had economic value. ”

He said the issue of how much your data is actually worth comes up most frequently when consumers sue companies and organizations for data breaches. If breach lawsuits survive initial hurdles, like whether plaintiffs have standing to sue, they settle before judges and juries can rule on big picture questions including the value of data, according to McGeveran’s research.

“There’s literally zero cases that go to a jury,” he told MarketWatch.

The question of how much a consumer’s data is worth is crucial because consumers can only claim they were harmed by something like a data breach if they lost something of value — in other words, if their data had economic value.

From judges to lawmakers to academics, McGeveran said the big debate boils down to this question: “Are privacy invasions wrong just because? Or are they only wrong when something bad happens as a result?”

“ Senator Mark Warner, a Democrat from Virginia, is drafting a bill that would make companies like Facebook and Google inform users on the value of their data. ”

Government lawyers will want to know any court consensus on the worth of someone’s data if they ever opt to file antitrust lawsuits and have to convince a judge that Big Tech needs a breakup.

If there’s little legal agreement on the value of data in the privacy context, there’s even less case law on the value of personal data in antitrust matters, said Avery Gardiner, a senior fellow at the Center for Democracy & Technology.

Consumers don’t spend any money to access sites like Google or Facebook, but monetary cost — or the lack of it — isn’t the only way to think about possible anticompetitive practices, she said. Stifled innovation and poor product quality could also be examples of anti-competitive practices, Gardiner said.

But before any cases get filed, Gardiner said any investigation would have to follow the facts to determine whether consumers or competitors were harmed. “Big isn’t bad,” she said. “Anticompetitive is bad.”

“ In California, Gov. Gavin Newsom, a Democrat, is calling for a ‘data dividend’ that could make businesses pay consumers for the personal data they provide. ”

Indeed, the antitrust matters in the news might never turn into any cases at all. Facebook, Amazon, and Apple did not reply to a request for comment and a Google spokesman declined to comment. On Tuesday, Tim Cook, Apple’s CEO, told CBS News US:CBS that government scrutiny was fair, but “we are not a monopoly.”

Judges and lawyers aren’t the only ones grappling with the value of data.

Senator Mark Warner, a Democrat from Virginia, is drafting a bill that would make companies like Facebook and Google inform users about the value of their data. Rachel Cohen, a spokeswoman for Warner, said the senator is aiming to introduce the bill by the end of June. In California — where stiff privacy rules take effect in 2020 — Gov. Gavin Newsom, a Democrat, is calling for a “data dividend” that could make businesses pay consumers for the personal data they provide.

‘A world of ambiguity’

Last September, hackers attacked Facebook and exposed the personal information of approximately 29 million users. Some Facebook users turned around and sued the site.

In court papers to dismiss the case, Facebook’s lawyers said the vulnerability was quickly patched and the stolen information could have included “basic contact information” users had on their profile, and, in other cases, extra information like religious views and relationship status.

The lawsuit “spins a speculative tale” of all the harm that could theoretically happen, lawyers for the social-media platform said when they asked the judge to dismiss the case. The plaintiffs didn’t “assert that such data was actually stolen from any Facebook user or that plaintiffs actually suffered any cognizable harm in the wake of the attack, let alone a harm traceable to Facebook’s conduct,” the lawyers said.

“ ‘Tech companies have exploited uncertainty around whether data has economic value. They basically use this ambiguity to collect this data.’ ” — Katharina Pistor, Columbia Law School

The dismissal bid was “cynical,” according to the plaintiffs’ lawyers. They said Facebook denigrates the personally identifiable information it coaxes consumers to provide, but then monetizes that data to generate billions of dollars in revenue, asserting that this information lacks any value to hackers.

The Northern District of California case is pending before Judge William Alsup.

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Cases like the one unfolding in federal court are happening “in a world of ambiguity,” according to Katharina Pistor, a professor of comparative law at Columbia Law School and director of the school’s Center on Global Legal Transformation.

Pistor, author of “The Code of Capital: How the Law Creates Wealth and Inequality,” said, “We are still in a world with a degree of uncertainty as to how to legally categorize data.” She later added, “Tech companies have exploited uncertainty around the sort of questions on what data is, and whether data has economic value. They basically use this ambiguity to collect this data, capture it and claim it as their own.”

“ America’s privacy laws are piecemeal, with the presumption that data collection. In Europe, data collection is forbidden unless it’s allowed by law. ”

McGeveran noted that America’s privacy laws are piecemeal, with the presumption that data collection is allowed if no rule says it isn’t. In Europe, it works the opposite way — there, data collection is forbidden unless it’s expressly allowed by law. And many other industrialized countries follow the European model, he said. “The U.S. is definitely unique in its approach,” he observed.

European regulators have been taking action against the big tech companies now being scrutinized in America. For example, in less than two years, European antitrust regulators have fined Google over $9 billion in three sanctioning instances. The company is appealing all three.

Like the legal value of data, Gardiner said there are also plenty of question marks over how to build a case busting up a monopoly. “Antitrust law is like reading tarot cards,” she said. “You’re trying to say what will happen in the future of this market. It’s a guessing game.”

Facebook shares are up more than 28% from the start of the year, while Amazon shares are up more than 15% in that time. Apple shares are up about 16% though Google shares are slightly down, off .6%.