Facebook's Mark Zuckerberg, Google's Sundar Pichai, Apple's Tim Cook and Amazon's Jeff Bezos are set to testify at a hearing in Congress on "online platforms and market dominance"

Antitrust fever hits a peak in Washington this week with lawmakers set to grill top executives of four of the biggest US technology firms in what promises to be a rare political spectacle for the digital era.

The showdown Wednesday in the House of Representatives comes amid rising concerns over Big Tech dominance, which has become even more pronounced during the coronavirus pandemic.

The unprecedented joint appearance in the House Judiciary Committee will include chief executives Tim Cook of Apple, Jeff Bezos of Amazon, Mark Zuckerberg of Facebook and Sundar Pichai of Google and its parent firm Alphabet. All will testify remotely.

The hearing is part of a probe into " and market power," taking place as US and states conduct their own investigations.

"This is the Super Bowl of antitrust," said Avery Gardiner, an antitrust expert at the Center for Democracy & Technology.

She said the hearing offers a timely way to focus on key issues around competition and concentration of economic power.

"People are feeling frustrated with the way our society is organized, and antitrust is one tool to go after powerful companies," she said.

But current US antitrust laws make it difficult for enforcers to target companies simply for being large or dominant without showing harm to consumers or abuse of market power.

Because of that, "the real purpose of the hearing is theatrical, and tied to the politicians' electoral interests," said Christopher Sagers, a law professor specializing in antitrust at Cleveland State University.

Eric Goldman, director of the High-Tech Law Institute at Santa Clara University, said politicians see a benefit in attacking the tech firms and ironically, "they will be looking for that viral YouTube moment."

The hearing takes place against a backdrop of antitrust investigations that are underway involving the US Department of Justice, the Federal Trade Commission and nearly all state law enforcement agencies as well as authorities in Europe and elsewhere.

Big Tech firms such as Google, Amazon, Facebook and Apple have seen their market value rise amid the pandemic-induced economic crisis

Muddying the waters

But the antitrust debate is being muddled by rising "techlash" over a range of issues from privacy to economic inequality.

Social media giants face attacks for allegedly using their dominance to stifle free speech due to a bias against conservatives, a claim made by President Donald Trump.

Other activists argue Facebook fails to curb hateful content promoting violence, including from Trump.

Any effort to use to enforce would run into constitutional concerns, raising the specter of a "government censor," according to Sagers.

"My fear is that members of Congress will have a hard time sticking to antitrust and we'll hear a lof of questions about privacy, content moderation, worker conditions," said Gardiner.

"These are important issues, but they are not about antitrust."

Facebook could come under scrutiny for its acquisition of nascent rivals which critics say squelched competition and increased its dominance of social media, according to Sagers.

Smaller rivals have long complained about the difficulties of competing against the giants: Yelp argues that Google favors its own sites and demotes the rival review service; Spotify says Apple Music has an unfair advantage on the iPhone maker's platform.

Slow wheels of change

Experts say there are limited remedies under existing law and precedent to deal with tech platform dominance.

Representative David Cicilline chairs the committee holding Monday's hearing with Big Tech CEOs

But any quick revision of antitrust law seems unlikely, given the muddled political picture and Congress' slowness.

Antitrust enforcers face a delicate task because "it is not illegal to be big," said Gardiner.

Investigators must identify "abuse of market power" which is difficult to define, she said.

Even then, it may be hard to craft a remedy in the public interest because of the benefits offered by the massive scale of the tech platforms.

"You don't want to have to check 11 different social media sites for pictures of your kids on Halloween," Gardiner said.

"There is a benefit to having more people on the platform."

Still, Gardiner sees a strong possibility of at least one antitrust lawsuit being filed this year, although "I don't expect a resolution for at least three years."

Some analysts say antitrust enforcement may not be best way to deal with the abuses of dominant firms in areas such as privacy, fairness and data protection.

"Antitrust cannot be the sole tool to address all the thorny issues that the platforms present," said Charlotte Slaiman of the consumer nonprofit group Public Knowledge.

"The best solution would be creating a new digital platform-focused agency to regulate the platforms. Because antitrust cannot do enough by itself to expand competition and innovation, such an agency is needed to rein in potential abuses by dominant platforms."