Trump's gone, but leaders still lie. Stay vigilant and demand the truth.

• We exercised our BS-detecting muscles under Trump, and we need to keep it up during the Biden era and beyond.
• Don't give politicians and authority figures the benefit of the doubt: demand receipts.
• Whether it's police unions or the CDC, Andrew Cuomo or Alexandria Ocasio-Cortez — it's in the public interest to always call out lies and demand the truth.
• This is an opinion column. The thoughts expressed are those of the author.

Donald Trump's constant lying defined his presidency.

More than incompetence, vulgarity, and cruelty - it was the 45th president's allergy to the truth that informed the rest of his administration's other toxicities.

It was only two days into his presidency that Kellyanne Conway offered the phrase "alternative facts" in defense of White House Press Secretary Sean Spicer's lies about the comparatively small crowd at Trump's inauguration.

Trump's presidency concluded with his insistence on a truly "Big Lie" - that the 2020 election had been stolen from as part of a conspiracy that no one has yet cogently explained and which has been laughed out of scores of courtrooms, including the Supreme Court.

In the exhausting four years between, the chief executive relentlessly lied over everything from the weather to the lethality of COVID.

Fact-checking presidents has long been a staple of journalism, but by necessity it went into high gear documenting and debunking Trump's lies - big and small, with the "Trump's lies" beat becoming its own cottage industry. It was a public service.

Now that Trump's in the Mar-a-Lago self-exile phase of his political career, we shouldn't let down our guard.

We need to just as vigorously fact-check President Joe Biden and his administration, as well as all elected officials and institutional authority figures.

Keep your BS detector well-tuned

Don't get me wrong, there's little reason to believe Biden will lie as prodigiously over inconsequential matters as his predecessor.

Trump's lies were part of a deeply-ingrained pattern and an authoritarian attempt to destroy the public's perception of reality.

But Biden will lie, dissemble, and obscure the truth when it serves his interests. All presidents do, as Adam Serwer wrote in The Atlantic. They lie about wars, affairs, healthcare policies, and anything else they'd rather the citizenry not know.

With nearly a half-century in government, Biden's already lied plenty, a somewhat recent example being his ridiculous campaign trail whopper about getting arrested while trying to visit Nelson Mandela in a South African prison.

"These are deceptions, not mere errors of fact, which all mortals make," Serwer wrote of past presidential lies. Now that Biden's president, his inevitable lies will be some of the most consequential in the world.

And it's not just lies from the White House that remain of great consequence. We - the media and the general citizenry - need to continue exercising the diligence learned from calling out Trump's lies, to more effectively root out mistruths wherever they affect public life.

New York Gov. Andrew Cuomo, as prominently-lauded as any state-level official has been in a long time, lied and deceived the public. He's also kept vital public information under tight lock-and-key, far from public scrutiny.

For months he has offered conflicting and mutually-cancelling explanations for his administration ordering nursing homes to accept COVID patients, and for the huge spike in nursing home deaths that erupted shortly thereafter. If any one of Cuomo's excuses were the truth, they'd make lies of the others.

Thankfully, a report from the state's attorney general Letitia James confirmed that they were all lies, and that the state's health department had been cleverly cooking the books by undercounting nursing home deaths by about 50%.

These, too, aren't mere errors of facts. These are lies and using the power of the governorship to withhold vital information from the public.

Beyond politicians and the media, there is a crisis of confidence in institutions.

The Centers for Disease Control manipulated the public by discouraging mask use at the start of the pandemic to prevent hoarding of hospital grade N95 masks, and as a result, now faces skepticism over its current guidance on post-vaccination mask-wearing.

The "big tech" social media companies are hated by the left for not sufficiently policing misinformation on their platforms, while being hated by the right for a perception of politically biased censorship.

And as 2020 showed us again and again, police departments and their unions lie all the time.

Truth matters, no matter who's president. Don't sell it out for political convenience.

Rep. Alexandria Ocasio-Cortez in one of her first interviews after taking office in 2019 brushed off Anderson Cooper's question about a "four Pinocchio" rating she received in a Washington Post fact check.

At issue was a tweet about unaccounted Pentagon spending that was wildly off-base from a factual perspective.

"It's unconvincing to try to pass this off as a rhetorical point being misread," the Post's fact-check read before noting, "The tweet is still up, probably causing confusion."

At the mention of this fact check, Ocasio-Cortez lamented to Cooper: "I think that there's a lot of people more concerned about being precisely, factually, and semantically correct than about being morally right."

Two years later, AOC's factually incorrect tweet is still up.

Ocasio-Cortez has it precisely backward. Lies and hyperbole undermine morals and ethics, regardless of politics. If the arguments used to back a cause aren't based in reality, the arguments are misdirections, and without merit.

A self-granted claim of "morality" is no defense, just as it wouldn't be when anti-abortion groups traffic in misinformation to justify their own cause, which they surely believe to be "morally right."

We, the public, need to be cynical about authority regardless of which side is in power.

That doesn't mean a knee-jerk disrespect or an implicit opposition to authority at all turns. It just means we should demand receipts.

If elected officials and institutional leaders won't back up their claims or let the public see what's under the hood, we shouldn't give them the benefit of the doubt and assume they've got nothing to hide.

Our fact-checking and bullshit-detecting muscles were made stronger by Trump. Let's keep using them now that he's gone.