The Supreme Court effectively has taken over the work of regulating campaign finance by striking down congressional efforts to restrict money in politics and substituting more permissive standards. The first such decision, Buckley v. Valeo, in 1976, held that election spending is a form of constitutionally protected free speech, although it permitted some restrictions to prevent corruption. Under Chief Justice John Roberts, who was installed in 2005, the court has issued a series of rulings significantly expanding what counts as free speech while simultaneously restricting what can be done to prevent corruption.

In Citizens United, the court struck down restrictions on election spending by corporations and unions, leaving only flimsy prohibitions on giving the money to a candidate or taking instructions from a candidate. The court justified this stance by defining political corruption narrowly — as quid pro quo arrangements in which donations effectively purchase desired political outcomes — and then concluding that the protections it had preserved were sufficient.

Mr. Trump, whose administration has been shaped by his willingness to stretch the law, is providing an object lesson in the consequences of the court’s capacious standards. There’s no reason to think the April 2018 dinner was an unusual event.

The unusual part is only that it was taped by one of the supplicants, Mr. Fruman. The guests were donors or potential donors to America First Action SuperPAC, a political organization with no legal ties to Mr. Trump that still managed to obtain more than an hour of the single most valuable commodity in Washington: the president’s time.

Such super PACs are vehicles for complying with the letter of the law by maintaining the legal fiction that their spending is not controlled by any particular politician or party, while still allowing donors to feel confident that the money will be used for a specific purpose and that the beneficiaries — but often not the general public — will know who deserves their thanks.

Barry Zekelman, the billionaire who spoke with Mr. Trump about steel making, is a Canadian who does not hold American citizenship and therefore cannot legally make donations to American politicians or to super PACs. Instead, Wheatland Tube, an American company that Mr. Zekelman partly owns, donated the $1.75 million to America First Action.

Mr. Zekelman complained to Mr. Trump that mandatory rest breaks for truck drivers made it harder to move his steel pipes to market — and also that they might force a driver to pull over when the driver was close to home. Mr. Trump expressed surprise that the government could enforce such a rule. “They have a method that you shut down a truck?” he asked. “Wow.”