While many country’s bribery laws require an express quid pro quo—an agreement to exchange a specific benefit for a specific exercise of government power—in practice many corrupt relationships involve implicit quid pro quos, in which the private party provides something of value to government officials, and the government officials use their power to help their private benefactors, but there is never any express agreement, or even any direct connection between any individual official act and a particular benefit conferred by the private party. The context in which such implicit quid pro quos are most widely suspected and discussed is perhaps campaign finance in democracies, but such implicit quid pro quos can occur in many other contexts as well. It is often very difficult—not only for law enforcement agencies, but also for empirical researchers—to find sufficiently clear evidence of an implicit corrupt deal. Yet quantitative empirical researchers have been making important strides in using available data to detect evidence of hidden or implicit wrongdoing—an approach sometimes dubbed “forensic economics.”

A fascinating recent paper by Sumit Agarwal, Wenlan Qian, Amit Seru, and Jian Zhang (forthcoming in the Journal of Financial Economics) illustrates both the potential and limitations of this approach. The paper, entitled “Disguised Corruption: Evidence from Consumer Credit in China,” presents quantitative evidence of an implicit quid pro quo between a large Chinese bank and government officials who wield regulatory authority over the bank. The paper finds that the bank offers unusually favorable lending terms to government employees (the “quid”) and that in those provinces where this practice is more widespread, the bank receives more favorable treatment from governments (the “quo”). While this evidence alone cannot establish that there was an implicit exchange (the “pro”), the authors suggest that this is the most plausible explanation of the data.

The data is certainly susceptible to that interpretation, but there are other, more benign possibilities. I’ll first say a bit more about the main evidence the paper offers for an implicit quid pro quo, and then suggest (though not necessarily urge) a possible alternative explanation.

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