The Department of Justice is investigating Big Tech companies for antitrust violations, and it’s basically a case of DOJ vs. DOJ. 

That’s because in preparation for just this sort of thing, firms have lawyered up — with hundreds of attorneys hired away from DOJ.

Big Tech companies — Google, Apple, Facebook, Amazon, Microsoft and HP — have hired at least 360 lawyers from the Department of Justice since 2011, found government watchdog American Accountability Foundation.

That’s 30 dozen lawyers.

Government employees retire early, of course, and often go on to other jobs.

And there’s nothing wrong with someone leaving government at an earlier age to seek more lucrative employment.

Heck, even judges do it, like Michael Luttig, a federal appeals judge who left the bench to work for Boeing.

But when the regulators go to work for those they regulated — at a big boost in pay — it’s more concerning.

There are several potential kinds of corruption in this revolving-door phenomenon.

One is the risk that government lawyers will be soft on the companies they regulate in hopes of later receiving big-bucks jobs from them.

Another is that they’ll promulgate overly complex regulations so that the companies they regulate will be pressured to hire the only people who understand those regulations, the people who drafted them.

(And there’s not really a contradiction here, because overly complex regulations typically benefit the kind of big, rich corporations that can afford to hire former bureaucrats for big bucks, at the expense of smaller competitors who can’t.)

There’s also the risk that hiring former bureaucrats increases the temptation of those working for the government to go easy so they can have a lucrative job someday too.

Every time good old Joe or Jenny from the department comes by to meet in an expensive suit and with a fancy briefcase, it’s a reminder of what could be.

There’s even more leverage when the former bureaucrats know where the bodies are buried in their old departments — and there are always “bodies,” at least of the metaphorical sort.

This is all textbook political science and administrative law — in fact, it’s right there in the textbook I use for my administrative-law classes.

The classic term for it is “agency capture,” in which the ostensibly regulated industry winds up “capturing” the agency that’s supposed to regulate it, obtaining protection from regulation it doesn’t want and often complicity in regulations it does want.

But there’s something worse going on nowadays. In modern America, both the Department of Justice and the upper echelons of corporate America — especially in the tech world — are largely prisoners of woke ideology.

The political contributions of bureaucrats and tech executives go overwhelmingly to Democrats.

Big corporations adopt diversity, equity and inclusion policies that are as radical as any university’s, work to silence Democrats’ opponents in the media — as Twitter did to this newspaper when it (truthfully) reported what was on Hunter Biden’s laptop — and in fact move back and forth, working tirelessly in both places to advance a single agenda.

James Madison wrote that the very definition of tyranny is the accumulation of all power in a single set of hands.

He was writing about government power, but nothing like the mega-corporations of today existed in 1789.

Today’s companies — again, especially Big Tech — often act hand in hand with government in compelling or punishing the government’s political opponents. And the government often steers corporations in its preferred direction.

This is made easier, of course, when it has people on both sides of every regulatory matter, as is the case with DOJ and Big Tech.

So what should we do? I’ve long argued for a 50% “revolving-door surtax” on officials’ post-government earnings if they go to work for those they oversaw: for the first five years after leaving government, 50% (on top of existing liability) for every dollar earned above the federal salary.

Why not? We tax “windfall profits” all the time, and when you profit from having worked for the feds, you’re profiting off work that was supposed to be for taxpayers’ benefit. Let taxpayers take their half.

There should also be stricter rules on post-government employment. And more (political) diversity in government hiring. But mostly, less revolving-door traffic.

When Barack Obama ran for office in 2008, he promised to “close the revolving door.”

That didn’t happen while he was in office — but that’s no reason it shouldn’t happen now.

Glenn Harlan Reynolds is a professor of law at the University of Tennessee and founder of the InstaPundit.com blog.