Quo

[…]; but what is the quo for which they ought to give the quid? you say they ought to give a quid pro quo; what is the quo? […]; the quo there was the taking up of the streets? […]; did not they give you a pretty handsome quid for the quo there?

Quid pro quo benefits are by nature differentially available to individuals, depending upon the quo—upon what promise has been made or performance provided.

Indeed, asymmetry precludes the possibility of pointing to any particular quo that is meant to recompense the quid. If an erstwhile case of criminal bribery bleeds into a lesser violation of the prophylactic gift rules as an identifable^([sic]) quo moves beyond view, then in similar fashion the quid pro quos we popularly debate descend into tokens of affection and regard as the quo'''s begin to fluctuate wildly in value. If there exists any kind of inequity between quid and quo, then—on this line of argument—the expansive category of “friendship” emerges to account for it, siphoning the situation away from the class of objectionable quid pro quo. The claim officials here make—that for a quid to have a quo there must be some equivalency between the two—draws theoretical sustenance from the objective, exclusionary approach that critics of classical contract law apply to disproportionate exchanges.

Corruption, the Court declared in Buckley v. Valeo, involves a quid pro quo: an officeholder doing something in office in return for money or some other favor provided by another individual or entity (for our purposes, a corporation). The problem, however, is that in principle there can be a quid—the money or favor offered by the business to the official—and a quo—the action taken by the official that benefits the business—without any clear evidence of a pro, that is, that the two are connected.[…]The “pro,” the connection between quid and quo, might take place only inside the minds of the official and businessperson concerned.[…]What this means is that we cannot use the quo itself as indirect evidence for the pro.

It is hard to pull off a quid pro quo if the holder of the quo doesn’t know about the quid.