Quid pro bono

Where a service is provided on its face pro bono (without payment), but the length of time spent and the complexity of the service means it is likely there is a quid pro quo settlement of the debt occurring somewhere quietly in the background.

The lawyers were acting for the defendant pro bono, but people suspected that it was actually a quid pro bono arrangement as there was no way the lawyer would work for that guilty defendant for free for so long.