Democrats have argued for the past three years that the investigation into then-candidate Donald Trump’s potential ties to Russia was not only legal, but also necessary as a matter of national security.

“If a foreign power possessed compromising information on a U.S. government official in a position of influence, that is a counterintelligence risk. If a foreign power possessed leverage, or the perception of it, over the president, that is a counterintelligence nightmare,” House Intelligence Committee chairman Rep. Adam Schiff wrote in a Washington Post op-ed in April.

The same exact logic applies to Joe Biden.

The fact that his son, Hunter Biden, was appointed to a lucrative board position at Burisma in 2014 while he himself was overseeing the Obama administration’s policy toward Ukraine created a conflict of interest so problematic that Obama administration officials had to brief Ambassador Marie Yovanovitch about it before her Senate confirmation hearing in 2016. (They did nothing to resolve it.)

It seems Hunter Biden made a habit of enriching himself by exploiting his father’s position. Even if Vice President Biden did the right thing in 2016 by demanding Ukraine fire an allegedly corrupt prosecutor, on pain of losing $1 billion in U.S. aid, and even if the investigation into Burisma was dormant at the time, he ought to have recused himself. Worse, Joe Biden has given confusing answers about whether he knew of his son’s business activities.

We do not yet know the truth about the Bidens — and, worse, we do not know what Ukraine knows (or China, where Hunter Biden also pursued business opportunities allegedly opened up by his father’s political position).

As Democrats have argued in the past, it would be a “counterintelligence nightmare” if a “foreign power” had “compromising information” or “leverage” over a president. We ought to know about that before Biden takes office.

The same logic Democrats applied to investigating Trump’s (imaginary) Russia ties justifies the investigation into Biden’s (real) Ukraine links.

When President Trump asked Ukrainian President Volodymyr Zelensky in July to investigate the circumstances in which then-Vice President Joe Biden forced out the prosecutor — and his demand was limited to that — he was acting on what Democrats themselves have described often as an urgent national security interest.

And unlike the Obama administration, which may have misled a FISA court to obtain surveillance warrants, Trump made the request lawfully, referring Zelensky to the Attorney General.

There is a clear dilemma in both the Trump-Russia investigation and the Biden-Ukraine investigation: it is hard to separate the public interest from political motives, especially in an election year. Likewise with the investigation into Hillary Clinton’s misuse of a private email server, which was marred by politics.

Some of the FBI and CIA officials who investigated Trump, like Peter Strzok, clearly had partisan designs. But some appear to have believed, sincerely, they were acting in the best interest of the country.

The inherent risk of partisanship in an election-year investigation is a puzzle that requires a legislative solution. Perhaps Congress could create a separate office in the Department of Justice, overseen by a bipartisan panel of legislators, to handle such sensitive investigations in future in a way that screens politics out of the process.

But because Democrats believed so fervently in the Russia collusion hoax, they refused to see the potential abuses of power in the investigation. Now they will impeach Trump for doing what they said the government ought to do.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He earned an A.B. in Social Studies and Environmental Science and Public Policy from Harvard College, and a J.D. from Harvard Law School. He is a winner of the 2018 Robert Novak Journalism Alumni Fellowship. He is also the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.