It’s deja vu all over again: The second impeachment trial, the second national reckoning over the awful Capitol siege, the latest Trump melodrama.

Now that the opposing sides have filed their legal briefs, the reality of next week’s trial is hitting home--a largely academic exercise in which everyone in America knows the former president will be acquitted.

I’ve said that Donald Trump is actually being tried in the court of public opinion, but there may be higher stakes here than just one man’s reputation.

First, the legal arguments. The House impeachment managers told the Senate that Trump was "singularly responsible" for the death and destruction caused by his supporters: "He summoned a mob to Washington, exhorted them into a frenzy, and aimed them like a loaded cannon down Pennsylvania Avenue."

If that isn’t an impeachable offense, the 80-page brief said, "it is hard to imagine what would be."

Trump’s new lawyers, Bruce Castor and David Schoen, turned in a 14-page document in which "United States" was misspelled in the first sentence. (Ah, the lost art of proofreading.)

They denied the incitement charge and focused on the process argument that the Senate "lacks jurisdiction" to convict a president who is no longer in office.

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But it was the sparring over the First Amendment that was most striking.

Castor and Schoen faced a dilemma, given that Trump is reported to have dumped his previous attorneys because they wouldn’t argue the election was stolen.

So instead of contending that Joe Biden didn’t win the election, they say Trump believed he "won it by a landslide." With that belief, he had the First Amendment right to "express his belief that the election results were suspect." And by the way, there was "insufficient evidence" to show the ex-president was wrong.

Well, a president does have free speech rights. But under the shouting-fire-in-a-crowded-theater argument, that can cross the line into incitement. And the Democrats, who plan to show lots of video of the violence, say Trump backers are heard yelling "invade the Capitol building" after listening to him.

The notion that Trump genuinely believed he was robbed flies in the face of all the court judgments and his own Justice Department. Liberals say the lie about the stolen election was what fueled violence among his fervent supporters. But the trial won’t turn on that argument.

Beyond Trump’s preordained fate, this is really a proxy war over the future of both parties--not just the narrow question of whether the ex-POTUS can run in 2024.

The Democrats want to run against the Trump Party for a generation, much as they ran against Herbert Hoover for decades and Republicans ran against Jimmy Carter through several cycles.

They are laying the foundation not just for the 45 or so Republican senators who will vote to acquit, but for the House Republicans who challenged the Electoral College results. And beyond that, they want to tar most of the 74 million Trump voters as buying into the election-fraud allegations (blurring the fact that the vast majority are law-abiding Americans who were appalled by the Capitol attack).

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By ramping up the attack on Marjorie Taylor Greene and her conspiracy theories, Democrats are making the case that leading Trumpists dwell in an alternate reality that includes violent fantasies.

For Republicans, the goal is to avoid being branded a party that refused to accept a legal election, whipped up its supporters with false narrative and was complicit in the Capitol attack. And they have to do that without alienating the majority of GOP voters who still love Trump.

On one point, both parties appear to agree: disposing of the impeachment trial in less than a week.