High-profile lawyer Abbe Lowell again entered the national spotlight this week representing Hunter Biden in the legal battle involving his infamous laptop, and Lowell's hiring signals how seriously Biden is taking his situation, an attorney tells Fox News Digital.

"Abbe is not cheap, and you don't bring in Abbe unless you want to go to war or prevent one," said the source who's worked with Lowell. "They're going on the offensive. He hasn't been charged with anything, but they're trying to prevent that because that would be bad for [President] Biden and Hunter."

Lowell made a splash this week with letters urging prosecutors to launch state and federal investigations into John Paul Mac Isaac, who he accused of "unlawfully" accessing the younger Biden's personal data on his laptop after it was left at his repair shop in 2019. Former President Donald Trump’s lawyer Rudy Giuliani, Steve Bannon and other notable Biden critics were also listed in the lawsuit for their role in disseminating the information to the public.

"Mr. Mac Isaac chose to work with President Donald Trump’s personal lawyer to weaponize Mr. Biden’s personal computer data against his father, Joseph R. Biden, by unlawfully causing the provision of Mr. Biden’s personal data to the New York Post," Lowell wrote Wednesday.

Abe Lowell at John McCain's funeral

High-profile attorney Abbe Lowell has taken on Hunter Biden as a client as he wages a fierce legal battle over his infamous laptop. ( Tom Williams/CQ Roll Call)

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Cease and desist letters were also sent to others who obtained and disseminated the laptop's contents.

After critics reacted to the letters saying Hunter Biden was essentially confirming the laptop was his, Lowell pushed back, telling Fox News, "These letters do not confirm Mac Isaac’s or others’ versions of a so-called laptop. They address their conduct of seeking, manipulating and disseminating what they allege to be Mr. Biden’s personal data, wherever they claim to have gotten it." 

Abe Lowell

Abbe Lowell has been one of Washington, D.C.'s most recognizable high-power attorneys, representing some of the biggest names in politics. (Scott J. Ferrell/Congressional Quarterly/Getty Images)

His past client list includes Sen. Bob Menendez, D-N.J., former North Carolina Sen. John Edwards; and Jared Kushner, and the source says Lowell's hiring was both a telling and "brilliant" move by Biden. 

"Abbe is one of the best attorneys on Planet Earth, so hiring him from a strategic standpoint was a brilliant move," they said. "You couldn't find someone who can navigate Congress and the DOJ space better than him."

They also pointed to Lowell's ability to navigate Congress, where the new Republican majority is set to launch a series of investigations into the president's son, as well as the media attention any probe will get.

Lowell began his career in the Department of Justice from 1977-81, which included serving as a special assistant to Attorney General Benjamin Civiletti under the Carter administration. 

The United Nations High Commissioner for Human Right appointed Lowell as its special counselor from 1994-96 in its investigation and prosecution of human rights violations in Rwanda and the former Yugoslavia. 

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He was tapped by House Democrats as their chief minority counsel for the 1998 impeachment trial of President Bill Clinton following his affair with Monica Lewinsky. 

In 2012, Lowell represented Edwards, the former U.S. senator and presidential candidate, when he was accused of violating campaign finance laws. Edwards was found not guilty on one count, while mistrials were declared for the other charges.

Abe Lowell, John Edwards leave courthouse

Lowell represented former Democratic presidential candidate John Edwards in his 2012 trial over alleged campaign finance violations. (Chuck Liddy/Raleigh News & Observer/Tribune News Service via Getty Images)

In 2015, Lowell took on Menendez as a client, who was hit with corruption charges by the Justice Department.

A judge later declared a mistrial and the DOJ dropped all charges against the New Jersey Democrat. 

Abe Lowell and Sen. Robert Menendez speak to reporters

Lowell represented Sen. Bob Menendez, D-N.J., when the lawmaker was indicted in 2015 on corruption charges. (Kena Betancur/Getty Image)

More recently, Lowell appeared alongside Kushner as he testified in 2017 before the Senate Intelligence Committee investigating Russia's involvement in the 2016 presidential election.

Kushner is Trump's son-in-law and served as a top White House aide during the Trump presidency.

HUNTER BIDEN’S LAWYERS DEMAND CRIMINAL PROBE INTO LAPTOP LEAKERS, GIULIANI AND OTHERS, ADMIT LAPTOP IS HIS

Abbe Lowell and Jared Kushner in Senate building

Lowell represented Jared Kushner, son-in-law and top White House aide to then-President Donald Trump, during the Senate's investigation into Russia's involvement in the 2016 election. (Bill Clark/CQ Roll Call)

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Other big-name clients Lowell has had over the years include D.C. lobbyist Jack Abramoff, actor Steven Seagal and music icon Sean "Diddy" Combs. 

Lowell is a partner at the law firm Winston & Strawn.  

Fox News' Anders Hagstrom contributed to this report.