Google, Facebook and other tech giants face a summer of regulatory grilling as long-running investigations into potential anticompetitive practices likely come to a head.The big picture: Probes into the power of Big Tech launched by federal and state authorities are turning a year old, and observers expect action in the form of formal lawsuits and potentially damning reports — even as the companies have become a lifeline for Americans during the pandemic lockdown.What they're saying: "I think all of [the antitrust enforcers] have foreshadowed there would be some event by the end of the summer," said William Kovacic, a George Washington University law professor and former Federal Trade Commission chairman. "I think they’ve poured a lot of cement around their feet so they don’t have a lot of room to maneuver on this. They have to do something that indicates forward motion come early autumn."1. The Justice Department vs. Google: Attorney General Bill Barr has signaled his agency is full steam ahead on its investigation into Google, with The Wall Street Journal reporting the DOJ is preparing to bring a case as soon as this summer. The probe, which came to light in June 2019, includes a review of Google's position in the ad tech marketplace, and the Journal indicated investigators are also looking at Google's search practices. Obama-era antitrust enforcers recently outlined a roadmap for an antitrust case against Google based on the digital ad marketplace. Google argues the ad tech industry is crowded and competitive, saying its rivals in the space include household names like Amazon, AT&T, Facebook, Comcast and Oracle. 2. House Judiciary vs. Big Tech: The antitrust subcommittee's year-long investigation into competition in digital markets — focused on Amazon, Apple, Facebook and Google — is expected to wrap up in June.Chairman David Cicilline has said he wants to hear from the CEOs of the major companies, and put some muscle behind that request in a pointed letter to Amazon demanding testimony from CEO Jeff Bezos.Cicilline told Politico he wants to introduce legislation this year based on the report's recommendations, but it's unclear how far that will advance, given the pandemic.3. State attorneys general vs. Google and Facebook: State antitrust enforcers announced multi-state coalition investigations into both Google and Facebook last year. The Google probe, led by Texas Attorney General Ken Paxton, could lead to a lawsuit this fall, the WSJ reported. Paxton's office declined further comment.The Facebook investigation, led by New York Attorney General Letitia James, is proceeding despite the coronavirus pandemic. A spokesman declined to comment on the status of the investigation.4. The Federal Trade Commission vs. Facebook: Last July the social media giant revealed that the FTC was conducting an antitrust probe. Reports indicate the agency is reviewing whether Facebook's acquisitions of Instagram and WhatsApp were anticompetitive.While Chairman Joe Simons said earlier this year he'd like to see the agency's tech investigations wrap up by the end of the year, the FTC has also noted that the coronavirus pandemic could affect timelines of investigations overall."We are working with parties, both third parties and [civil investigative demand] recipient parties that are under investigation to address the timing constraints and the issues surrounding their ability to comply in a timely manner," Ian Conner, director of the FTC's competition bureau, told Axios. He declined comment on the Facebook investigation.Between the lines: Action by one enforcer could add pressure on others to act as well. "You can always explain why you’re taking longer, but I think the decision by one major institution to act does increase the sense of urgency to get your matter under way," said Kovacic, who said he expects lawsuits filed by the end of the year. "The sense that everyone is pressing ahead probably inspires added effort to reach that point of decision."Why it matters: Tech antitrust cases have a mixed record historically. Their impact on the industry and our lives is usually most felt not in specific remedies but in the power of the proceedings to tie down the giants.They tend to distract company leaders, discourage risk-taking at dominant firms, and clear space in the market for challengers.What's next: If antitrust lawsuits are formalized, companies and prosecutors will choose between pursuing a settlement of some kind or going to trial. If companies think a settlement makes sense for them, they might opt for a quick deal with a Republican administration.But they could also delay to see who wins in November and whether the election improves the political landscape for them.If cases go to trial, these conflicts could easily drag on for years.Go deeper:Tech's antitrust probes push on in the face of pandemicAntitrust clouds gather over emboldened tech giantsFor tech, antitrust is a fatal distraction