The second factor was a two-week programme called the Manne Economics Institute for Federal Judges, which ran from 1976 until 1998.
This was funded by businesses and conservative foundations, and involved an all-expenses-paid stay at a beachside hotel in Miami.
It was no holiday, however, even if those who went nicknamed the conference “Pareto in the Palms”.
The curriculum was extremely demanding, taught by economists including Friedman and Paul Samuelson, both of whom had won Nobel prizes.
By the early 1990s nearly half the federal judiciary had spent a few weeks in Miami.
Those who attended included two future justices on the Supreme Court: Clarence Thomas (an arch conservative) and Ruth Bader Ginsburg (his liberal counterpart).
Ginsburg would later surprise colleagues by voting with the conservative majority on antitrust cases, applying the so-called “consumer welfare standard” championed by the Manne programme.
This states that a corporate merger is anticompetitive only if it raises the price or reduces the quality of goods or services.
Ginsburg wrote that the instruction she received in Miami “was far more intense than the Florida sun”.
In a paper under review by the Quarterly Journal of Economics, Elliot Ash of ETH Zurich, Daniel Chen of Princeton University and Suresh Naidu of Columbia University treat the Manne programme as a natural experiment, comparing the decisions of every alumnus before and after their attendance at the conference.
They then use an artificial-intelligence approach called “word embedding” to assess the language in judges’ opinions in more than a million circuit- and district- court cases.
The researchers find that federal judges were more likely to use terms such as “efficiency” and “market”, and less likely to use those such as “discharged” and “revoke”, after time spent in Miami.
Manne alumni took what the authors characterised as the “conservative” stance on antitrust and other economic cases 30% more often in the years after attending.
They also imposed prison sentences 5% more frequently and of 25% greater length.
The effect became stronger still after 2005, when a Supreme Court decision gave federal judges greater discretion over sentencing.
That researchers are turning the unforgiving lens of economic analysis on law and economics itself is a promising trend.
The dismal science has come a long way since the heyday of the Chicago school.
Thanks in large part to the empiricism of behavioural economics, it is less wedded to abstractions like the perfectly rational actor.
This has softened some of the Chicago school’s harsher edges.
But it will nevertheless take time for judges to modify their approach.
As Mr Ash notes: “The Chicago school economists may all be retired or dead, but Manne alumni continue to be active members of the judiciary.”
In courtrooms across America, Mr Posner’s influence will live on for decades to come.