Criminal Court Judges Have Limited Gate-Keeping Function for Defense Experts

by admin on April 24, 2009

in Defending Drinking Drivers, Drunk Driving Attorney's Page, The Science of Breath and Blood Testing In DUI Cases

In Michigan nearly all drunk driving cases have either breath or blood evidence ostensibly showing that the driver was at or above the legal limit of .08 at the time he or she was driving.  The state of the law in Michigan is such that nearly all “technical” rule violations by the police in collecting this chemical evidence go to the weight rather than to the admissibility of the test results. 

In other words, the prosecutor gets to show the results to the jury, and if a problem exists, it’s up to the jury to decide what the problem means.  This is what lawyers and judges call going to the weight rather than to the admissibility of the evidence.

An expert witness and expert testimony is most often required when seeking to explain a problem with a breath or blood test.  The expert witness can explain to a jury how breath or blood testing works, and why there was a problem in a particular case.  This expert testimony is necessary in order that the jury give the breath or blood test the proper weight, or even disregard the test results altogether.

But prosecutors don’t like defense experts.  Consequently, it has now become commonplace for prosecutors to challenge defense experts before the trial by filing a motion to preclude their testimony.  If successful, the witness does not testify, and the accused has no way to raise his or her defense.  If the breath or blood test results come into evidence unchallenged the results will be a quick conviction.

These prosecutorial motions typically cite the case of Daubert v. Merrel Dow Pharmaceuticals, 509 US 579 (1993) and Michigan Rule of Evidence 702, which says:

Rule 702 Testimony by Experts

If the court determines that scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education may testify thereto in the form of an opinion or otherwise if (1) the testimony is based on sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.

The Prosecutor’s Arguments Ignore the Constitution:

I believe, however, that in raising these arguments in this way, prosecutors essentially set up a straw man because their Daubert/702 arguments avoid or circumvent the primary determination in any criminal case, which is whether or not the remedy of witness and/or defense preclusion passes Constitutional muster.  Said differently, a trial court must never allow the rules of evidence to supplant a citizen’s Constitutional rights.

Here is a sampling of how the appeals courts view this issue from the appropriate and primary Constitutional perspective:

“A defendant has a constitutionally guaranteed right to present a defense, which includes the right to call witnesses.” People v Yost, 278 Mich App 341, 379; 749 NW2d 753, 779 (2008)(citing US Const, Am VI; Const 1963, art 1, §20).  The right to present a defense in a criminal trial includes the right to “offer the testimony of witnesses, and to compel their attendance[.]” Washington v Texas, 388 US 14, 19 (1967).  A defendant in a criminal case has a “right to present the defendant’s version of the facts as well as the prosecution’s to the jury so it may decide where the truth lies.” Id. (emphasis added).

“Just as an accused has the right to confront the prosecution’s witnesses for the purpose of challenging their testimony, he has the right to present his own witnesses to establish a defense.  This right is a fundamental element of due process of law.” Id. (emphasis added).

It has been recognized that this right is not absolute, and the defendant must still adhere to rules of procedure that ensure fairness and reliability to determine guilt or innocence. Yost at 379; 749 NW2d at 779.  However, “the sanction of preclusion is extreme and should be limited to only the most egregious case. Id. (citing People v Merritt, 396 Mich 67, 82; 238 NW2d 31 (1976)(emphasis added).

Daubert does note apply to the Defense in Criminal Cases:

It is also my position that Daubert is simply not relevant to this case, or any criminal case for that matter, at least insofar as a defense expert or theory is concerned.   Daubert was of course a civil case.  A court’s gate-keeping function is decidedly different in a civil case than it is in a criminal case. 

First, neither party to a civil case has inherent Constitutional right to present a defense.  However, in a criminal case, a Daubert analysis that serves to exclude evidence thereby depriving a defendant of his right to present a defense is unconstitutional. 

On the other hand, a Daubert analysis of a government witness or theory is appropriate because again, a defendant has a right to be convicted through the exclusive use of reliable evidence as well as a right to not be convicted with evidence that is unreliable.  This is why much gun shot evidence is now largely inadmissible, and why fingerprint evidence has been called into question.  While Daubert might serve to preclude a government from using a particular type of evidence, it may not, under almost all circumstances, deprive a defendant from using the same evidence. 

Ultimately, this difference in standing between the government and the defendant is because, unlike in a civil case where the parties are on equal footing, in a criminal case the parties are not.  The old saying “what’s sauce for the goose is sauce for the gander” simply has no place in a criminal case.  An example of this Constitutionally required “double standard” is Chambers v. Mississippi, 410 U.S. 284, 302-03 (1973), where the Supreme Court held that Mississippi evidentiary rules regulating impeachment and hearsay cannot impair criminal defendant’s right to cross-examine witnesses and present witnesses in his defense. It may be surmised that these same rules may be used to regulate a prosecutor’s right to cross-examine.

Similarly, in a criminal case, 702 and Daubert can and should apply to the prosecutor’s scientific or technical theories, but must never apply to the defendant’s (except in the most egregious cases) because to do so is almost certainly to violate the defendant’s Constitutional rights.

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