In an attempt to forestall the House's impeachment proceedings, President Donald Trump has released summaries of calls with the Ukrainian president that he claims exonerate him. The main defense of Trump and his supporters continues to be that there was no quid pro quo: he did not expressly condition Ukraine's continued receipt of American foreign aid to defend against Russian aggression on an agreement by its president to criminally investigate the Bidens.

While the impeachment proceedings aim to determine whether or not such a threat was indeed made—and presumably would constitute grounds for charging an abuse of powers by Trump—it is worth noting that such a defense is becoming alarmingly commonplace. It echoes the president's main rejoinder to the Robert Mueller investigation regarding Russian interference with the 2016 elections: that although he may have sent strong signals welcoming such meddling, there was never any collusion with respect to it. In other words, Trump and his campaign never expressly agreed to Russian efforts to help him get elected, particularly in exchange for any favorable treatment Russia would receive if he won.

These quid pro quo defenses rest upon a troubling premise. They suggest that, although there may have been an implied understanding that aid would be withheld if Ukraine failed to investigate the Bidens or that Russian election assistance was welcome and would result in favorable treatment, because there were never any express agreements to this effect, no illegal or improper acts had been committed. In other words, "wink and nod understandings" are fair game in the rough and tumble of politics so long as no one crosses the thin red line. And political parties on both sides of the aisle seem to accede to this premise. Perhaps this explains why Trump did not fear releasing a Ukrainian call summary that can be read to suggest such a covert understanding, and, indeed, why he thinks it even clears him of wrongdoing.

It is worth asking how such a crabbed and cynical view of acceptable political behavior began to take root in the American consciousness. Many Americans might be surprised to learn that at least one potential contributor might be their top judicial institution: the U.S. Supreme Court. Although this troubling worldview certainly did not originate there, the court gave it a substantial stamp of approval in a pair of key decisions from the past decade.

In its 2010 decision in Citizens United v. Federal Election Commission, a sharply divided Supreme Court struck down on free speech grounds restrictions that Congress had placed on "independent" spending by corporations and unions to promote candidates for federal elections (independent in the sense that there was no formal agreement or coordination between the financiers and candidates about the spending—typically for attack ads targeting a favored candidate's opponent). Justice Anthony Kennedy, writing for the majority, rejected Congress' argument that such restrictions were necessary to prevent "wink and nod understandings" where candidates who benefited from such spending would give special access and influence to the entities that spent on their behalf. He reasoned that corruption concerns were legitimate only when quid pro quo bribery could be proven—that a corporation had expressly agreed to spend for a candidate in return for special legislative favors. Somewhat jarringly, he asserted that if monetary expenditures on a candidate's behalf resulted in special access and influence pursuant to implied expectations, that was perfectly fine since "[d]emocracy is premised on responsiveness." In other words, democracy assumes that if you have the bucks to scratch my back, then I'll scratch yours—so long as the scratchers are not careless enough to make their quid pro quo explicit.

This disturbing vision of a properly functioning democracy was bad enough. But only four years later, writing for a majority, Chief Justice John Roberts doubled down on it in another divided ruling, striking down on free speech grounds limits Congress had placed on the total amount of contributions any one person could give to federal candidates. Reasoning that total contribution limits would do nothing to stem quid pro quo bribery of a particular candidate by a donor, Roberts dismissed the notion that hefty blanket donations to a particular party could engender corruption. In his view, "[i]ngratiation and access … are not corruption. … They embody a central feature of democracy—that constituents support candidates who share their beliefs and interests, and candidates who are elected can be expected to be responsive to those concerns." Another strong defense of democratic back-scratching by the Supreme Court.

If our highest legal institution promotes such a view, can politicians then be blamed for feeling justified in inviting even foreign countries to grant them political favors so long as they avoid any sort of express quid pro quo in the process? By no means am I saying that this is what Kennedy or Roberts intended, but it is a lesson in how flawed reasoning by the highest court in the land might contribute to the adoption of behavioral norms that are damaging to a core precept of our republic: that governmental decisions should be based on what is best for the American people and not their self-dealing representatives.

Back to the Trump impeachment investigation. Most scholars who have studied the issue believe that the impeachable acts specified in the Constitution—"Treason, Bribery, or other high Crimes and Misdemeanors"—were intended by the Framers to include serious misconduct and not just criminal acts. After all, the sanction resulting from impeachment is mere removal from office and not any form of criminal punishment. Hence, even if the current House investigation concludes there is insufficient evidence of a quid pro quo agreement between Trump and the Ukrainian president of U.S. aid for a Biden investigation, but there is still compelling evidence of a tacit understanding, the question will remain as to whether serious misconduct should be construed to extend beyond the letter of the law to "winks and nods" as well.

Barry P. McDonald is a professor of law at Pepperdine University School of Law. He is an expert on the U.S. Supreme Court and constitutional law, having served as a law clerk for Chief Justice William H. Rehnquist.