Republican presidential candidate Donald Trump speaks during a campaign event at Trump International Hotel on Sept. 16 in Washington. (Evan Vucci/Associated Press)

Is the notoriously litigious Donald Trump afraid of getting sued by . . . Donald Trump?

If so, the plaintiff could have a pretty strong case.

This weekend, Americans learned that Trump reported losses in 1995 so yuge that he may not have paid any federal income taxes for 18 years. The Trump campaign has apparently decided that the best defense for this jaw-dropping behavior is a perversion of Judge Learned Hand’s famous ruling on tax planning. Hand determined that there was no legal obligation to maximize one’s payments to Uncle Sam; the Trump campaign is now insisting that its candidate has a legal obligation to minimize his payments to Uncle Sam.

Trump has “a fiduciary responsibility to his business, his family and his employees to pay no more tax than legally required,” the campaign said in a statement.

Likewise, campaign surrogate and former New York mayor Rudy Giuliani explained that Trump faced a serious legal liability had he not minimized his tax liability.

Following a New York Times report alleging that Donald Trump could have avoided paying federal income taxes for 18 years, former New York mayor Rudolph W. Giuliani and New Jersey Gov. Chris Christie on Oct. 2 said Trump’s handling of tax laws was “genius.” (The Washington Post)

“If he didn’t do it, he’d get sued,” Giuliani said on ABC’s “This Week.” He made this claim about Trump’s risk of a lawsuit seven times on that show. He made it thrice more on NBC’s “Meet the Press.”

Of course, even if you buy the argument that Trump had a “fiduciary duty” to investors to minimize the tax obligations of his corporations, partnerships and LLCs, the leaked documents in question were portions of Trump’s personal income tax returns, not any corporate or partnership income tax returns. So there were no investors to let down.

Whose wrathful litigiousness, then, compelled Trump to stiff the tax man? Who could have possibly sued Trump for wantonly dispensing too much of his own money to the feds?

Why, it must’ve been Trump himself, the only entity whom Trump has ever felt any “fiduciary duty” to enrich.

Maybe it seems ridiculous to suggest that Donald Trump might sue Donald Trump. How could he play both plaintiff and defendant? But recall that his confidants, and at times even the candidate himself, have argued that there are at least two of him to go around.

Plus, he has already sued or been sued by seemingly every other man, woman, child and corporation on earth, having been embroiled in more than 4,000 federal and state lawsuits. At the rate he’s going, he’ll eventually run out of legal adversaries who are not Donald Trump. Perhaps he knows he’s destined to one day sue the only man truly worthy of his legal jujitsu (i.e., himself).

Even without tax-planning shenanigans, mind you, Plaintiff Trump would have a nearly bulletproof case to make against Defendant Trump for breach of fiduciary duty. Defendant Trump is, through his alienating rhetoric, likely irreparably impairing the goodwill value of the gilded Trump name.

Already there are clues that his sexist, racist, vulgar and generally uncouth remarks have repelled customers from the Trump brand.

Bookings at Trump hotels seem to be down, according to a report from travel site Hipmunk. Foot traffic to Trump businesses appears to have also declined significantly during the presidential campaign, according to data from Foursquare. Trump-branded condo prices have lost the premium they enjoyed last year, according to an analysis from Redfin.

There have also been reports that his children are privately worried about the negative impact his erratic behavior is having on the family business.

Trump’s boorishness alone isn’t the only way he’s endangering his future income streams. His populist policy proposals, if successfully enacted, could also cripple many of the business strategies he has relied on to build his wealth.

Over the past year, Trump has whetted the public’s appetite for punishing business leaders who:

●Outsource production to factories abroad, as Trump does for shirts, suits, eyeglasses, crystal, vodka and hotel furnishings, among other Trump-branded paraphernalia.

●Employ undocumented workers, like those who have worked on Trump’s own construction projects.

●Rig the game against regular hardworking Americans, as he has done by stiffing small businesses for services fully rendered.

●Donate money to politicians in exchange for favors, as he has boasted he does.

●Engage in aggressive tax avoidance, as available tax documents now definitely prove he has engaged in.

He’s also advocated barring Muslim immigrants, some of whom have been known to stay at his own hotels.

If he continues to employ all these behaviors that he so vocally condemns, surely his supporters won’t tolerate the hypocrisy. Surely they’ll demand that such business practices be put off-limits to everyone, including Trump himself.

And Trump will only have himself to blame. It’s only a matter of time before that famous legal counterpuncher can consider himself self-served.