By Criminal Defense Lawyer Jeremy Rosenthal
The legal system encourages the accused to utilize expert witnesses and professionals to evaluate and advise during the investigation and defense of a case.
A lawyer has a duty to thoroughly investigate a case they are defending and it can be ineffective assistance of counsel not to do so. But let’s be clear – none of those duties are contingent on whether the lawyer thinks his client to be guilty or innocent.
Experts are Subject to the Attorney Client Privilege
An expert hired by the defense is part of the defense team. That means what they learn is privileged which makes it safe to learn bad facts the prosecution might not know.
Let’s use an example from a DWI case:
The police draw defendant’s blood, put it in a tube sealed and marked with a number then shipped to a lab where it goes into the mail room where some guy sorted it while he was on his phone then sent it to the analyst who only has 100 other samples to juggle that morning…. and then the result comes back looking much higher than the lawyer thinks it should be.
The lawyer can do a DNA test on the blood to see if they have the right person. But there is a big worry the DNA will match and defense just actually just found better evidence our own client is guilty than the prosecutor already has?!?
The rules protect this type of investigation and it’s actually possible to have blood retested or tested for DNA without the prosecution’s knowledge. Also, whatever Defense expert learns is privileged.
In the event the gamble worked – and it’s not Defendant’s blood — Defense expert can then testify about it on the witness stand before the Judge or Jury. Doing this would waive any privilege the expert had as part of the defense team.
In other words – the bad facts Defense expert learned can be kept secret or made public. Defense lawyers wouldn’t investigate their cases as thoroughly if they were worried learning bad facts would only assist in convicting their client.
Using an Expert to Evaluate – Not Testify
A good expert is one who is faithful to their discipline – not a particular outcome in any given case.
It is common for me to reach out to an expert and have them do an evaluation of a case only for them to tell me, “Jeremy I don’t think you want me to testify about this case.”
The expert can still assist by giving technical support as to how defense might handle a prosecution witness or by steering defense away from problematic defensive theories.
They Can Still Hurt Us Even if They Testify
Calling an expert witness is always a judgment call. Because the witness is loyal to their discipline and not the outcome – we have to recognize when Defense calls them to the stand — the privilege is essentially waived. Everything which went into their evaluation and opinion is discoverable by the prosecution.
This means the prosecution can draw out either harmful facts or data which can be used to undermine our defense.
The question is whether after balancing the harm versus benefit – it still makes sense to call an expert witness. This is where your lawyer’s experience is crucial.
*Jeremy Rosenthal is board certified in Criminal Law by the Texas Board of Legal Specialization. He is designated as a Texas Super Lawyer by Thomson Reuters.