Truly, to combat his assertion, you should find statistical evidence to show that his anecdotes are actually contrary to the trend.
Anecdotal evidence _is_ evidence. It is just not strong statistical evidence.
It is never my responsibility to disprove any assertion, as that is fundamentally impossible. It is the responsibility of the person making the assertion to provide a sufficient quantity of relevant evidence.
The old adage that 'you can't disprove a negative' is more specific in scope than your allusion to it here.
Mostly, however, the nature of collaborative argument is such that yes, we are disproving and attempting to disprove each other all the time.
I was, in fact, trying to highlight the fact that the larger number of prison inmates in the US compared to other countries cannot be attributed solely to corrupt law enforcement, judiciary and correctional systems. That's not saying they are perfect, but that is not the cause of the larger population and that, maybe, you could point your suspicions elsewhere.