Can Trump just 'show up' to give a State of the Union? Nope.
Donald Trump hasn’t shown an ounce of concern for any of the millions of Americans being hurt by his demanded federal government shutdown, but the moment he learned his actions would cost him the most lavish and flattering television appearance of the year, a State of the Union address, he suddenly found something to care about. Now comes the news that he’s threatening to just show up and give his speech anyway, regardless of whether House Speaker Nancy Pelosi and the rest of the House gives him permission, because of course he is. It’s the most Trump thing ever.
So, can he do that? No. He can’t do it, and it’s not worth even getting bothered over. His staff absolutely knows this as well, which makes the current outburst all the more pathetic, and there are a lot of individual rules and details involved, but from a logistical standpoint there’s no mechanism by which the White House can commandeer House chambers to hold a Joint Session of Congress on their own say-so.
Without both House and Senate resolutions to do so, there will not be a Joint Session for Trump to address. Senators will not be there. The House may be in session or in recess; if Pelosi wanted to send Congress home on Jan. 29 she could do so. And if House Democrats wanted to invite another possible speaker, perhaps a recently retired president with his own thoughts on the current situation, to give a speech on the day and hour Trump was planning to show up, they could do that as well.
What the presidency does give Donald Trump is the right to enter the House while it is in session and wander around the floor a bit. He is free to do so; he cannot, however, simply commandeer the dais and start shouting things out like an unusually angry improv comic. It is at this point that the Sergeant at Arms could possibly decide to cart the nice man off, if push came to shove, but a far more likely outcome would be for House leadership to put the House in recess, ordering the microphones turned off. C-SPAN coverage is, as we were rather frequently reminded of during the Paul Ryan era, fully at the discretion of the House Speaker; the cameras would immediately be turned off as well. And possibly the lights, so Trump had better bring along a flashlight.
Obviously, all of this gets extremely silly very quickly. To be sure, Donald Trump could smuggle in his smartphone and video himself giving a speech to nobody in a possibly dark and empty room. Given that the whole point of Trump’s fit is the denial, by Pelosi, of the pageantry of the State of the Union, it seems vanishingly unlikely he would willingly put himself in a position that would be mocked, relentlessly, for the rest of his term.