Defendants who can afford expensive private defense lawyers have a lower conviction rate than those who rely on court-appointed public defenders.
Conclusion (this explains why)
Criminals committing lucrative crimes (embezzlement, insider trading) are more successful at avoiding conviction than street criminals.
Premise
Defendants with expensive private lawyers have a lower conviction rate than those with court-appointed public defenders.
Evaluate
The evidence is Comparative (lower conviction rate), and the conclusion is Causal (this explains why).
That means we're dealing with the #1 argument pattern of Str / Wkn: Explain Curious Fact.
CURIOUS FACT Why do defendants with private defense lawyers have a lower conviction rate than those with public defenders?
i.e. why is having a private defense lawyer correlated with lower conviction rates and having a public defender correlated with higher conviction rates?
AUTHOR'S CAUSAL INTERPRETATION The more expensive lawyer is causing the lower conviction rate.
The author is also clearly assuming that defendants charged with embezzlement / insider trading are more likely to have a private defense lawyer, whereas street criminals are more likely to have a public defender.
Goal
When it comes to the Explain Curious Fact part of the argument, we can strengthen by ruling out an alternate explanation for the lower conviction rate of private defense lawyers (maybe they're not actually better lawyers, but their clients are just less often guilty and so it's easier to get an acquittal).
We could boost the plausibility of the author's causal story with any fact that makes it seem like private defense lawyers are more skilled at getting convictions than public defenders are.
Or we could strengthen by supporting the author's assumption that ppl charged with embezzlement / insider trading are more likely to have private defense, while street criminals are more likely to have public defenders.