Polygraph Tests in Michigan Domestic Violence Cases

A polygraph, or lie detector test, cannot be used as evidence at a Michigan trial. The rule bars the results of an examination and also evidence about whether a test was administered, whether the defendant was asked to take one, and whether the defendant was willing or unwilling to take one.^[1] A person charged only with domestic assault also has no statutory right to demand a test: that right is limited to people accused of the criminal sexual conduct offenses listed in the statute.^[2]

People on both sides of a domestic violence case ask about polygraphs. This page explains what the law allows, what it does not, and where the published Michigan sources are silent.

Why polygraph results are kept out

The Court of Appeals has called the rule that evidence relating to a polygraph examination is inadmissible a "bright-line rule," and it applies in criminal prosecutions and civil trials alike.^[1][5] Michigan courts give two reasons:

• Polygraphs have not gained the required degree of acceptance or standardization among scientists.^[5]
• Jurors may give disproportionate weight to the results and treat them as conclusive proof of guilt or innocence.^[5]

The rule cuts both ways. A defendant who passed a test cannot tell the jury so, and a prosecutor cannot tell the jury that a defendant failed or declined one.^[1]

Who has a right to a polygraph?

MCL 776.21(5) provides that a defendant who allegedly has committed a crime under the listed criminal sexual conduct sections "shall be given a polygraph examination or lie detector test if the defendant requests it."^[2] In People v Phillips the Michigan Supreme Court read that language to extend the right to demand a polygraph only to a defendant who allegedly committed an enumerated criminal sexual conduct violation.^[2]

Situation	What MCL 776.21 provides
Person accused of one of the listed criminal sexual conduct offenses	Must be given a polygraph if he or she requests it[2]
Person accused only of domestic assault or another offense not on the list	No statutory right to a polygraph[2]
Victim of one of the listed criminal sexual conduct offenses	A law enforcement officer may not request or order the victim to take a polygraph[6]

Domestic violence cases sometimes include a criminal sexual conduct count; where they do, the statute applies to a defendant alleged to have committed that offense.^[2] See Sexual assault within marriage. Even then, the right is a right to be given a test. It does not make the result admissible at trial.^[1]

What you say during a polygraph is a different matter

The exclusion covers the test. It does not cover the conversation. The Michigan Supreme Court held in People v Ray that statements made by a defendant before, during, or after the administration of a polygraph examination are not excludable per se.^[3]

Ray speaks of statements made before, during, and after the examination, so a police polygraph is best understood as an interview. Anything said in those conversations is subject to the ordinary rules on statements to police, including the rule that a person in custody must receive Miranda warnings before interrogation for the statements to be used.^[7] A statement a defendant made, offered against the defendant, is not hearsay.^[8] See Should you talk to police?

A polygraph arranged through a defense lawyer

A private examination arranged by a lawyer stands on different footing from a police examination. A statutory privilege applies to polygraph examiners, and information obtained by a polygraph examiner during an examination conducted at the request of an attorney is subject to the attorney-client privilege.^[9]

What a private result can accomplish is a separate question. It is not admissible at trial.^[1] Whether a prosecutor will take a privately obtained result into account when deciding what to charge or what plea to offer is a matter of that office's practice. The Michigan sources this guide relies on do not address it, and no court rule or statute in those sources gives a private polygraph any formal role in charging or plea decisions. For how those decisions are made, see Who decides to file charges and Plea bargains in domestic violence cases.

The two settings where a court may consider results

There are narrow exceptions outside the trial itself. Polygraph results may be admissible in support of a motion for a new trial, and a court has discretion to admit them in support of a motion to suppress illegally seized evidence.^[4] The conditions include that the results are offered on the defendant's behalf, that the test was taken voluntarily, that the examiner's qualifications, the equipment and the procedures are approved, and that the results are considered only with regard to the general credibility of the subject.^[4]

Sentencing is not one of those settings. A trial judge should not broach the subject of polygraph examinations or induce a defendant to take one for sentencing purposes; a presentence report should not contain the results unless the defendant consents; and a judge should not consider the results when sentencing.^[10]

What happens if a polygraph is mentioned at trial

A witness sometimes mentions a polygraph in passing. The mere mention does not automatically require a mistrial. Courts consider:^[11]

1. whether the defendant objected or sought a cautionary instruction;^[11]
2. whether the reference was inadvertent;^[11]
3. whether there were repeated references;^[11]
4. whether the reference was an attempt to bolster a witness's credibility;^[11]
5. whether the results of the test were admitted rather than merely the fact that a test had been conducted.^[11]

If polygraph evidence is admitted or improper argument is made about it, the court should immediately instruct the jury to disregard it and inform the jury of the unreliability of such tests.^[11]

The bar has an edge. In People v Wade, decided in 2025, testimony that a defendant became concerned with the mere prospect of a polygraph was held to be outside the rule, because nothing the jury heard suggested that the defendant took a polygraph, was asked to take one, or was willing or unwilling to take one.^[12]

Polygraphs and the complaining witness

People accused of domestic violence sometimes ask whether the person who made the report can be required to take a test. No source this guide relies on gives a defendant any such power. The only statute on the subject, MCL 776.21, bars officers from requesting or ordering a polygraph of a victim of the listed criminal sexual conduct offenses.^[6] Its definition of victim is tied to those offenses, so it does not speak to a complaining witness in a case that charges domestic assault alone.^[6]

Whatever any witness's polygraph might show, the results of a polygraph examination are not admissible in a criminal prosecution.^[5] A witness's credibility is tested in court through cross-examination and through earlier statements that differ from the testimony.^[13][14] Knowingly making a false report of a crime is a separate offense with its own elements.^[15] See False accusations of domestic violence.

Practical points before agreeing to any test

• A request from an officer to "come in and take a polygraph to clear this up" is a request for an interview. Speak with a lawyer first.
• A passing result does not by itself end a case, and a jury will not hear it.^[1]
• A result that goes badly in a police examination is not evidence either, but what was said in the room is not automatically excluded.^[1][3]
• A person on bond should confirm that the appointment does not conflict with any release condition.

Other early decisions that affect a case are collected in Mistakes to avoid after a domestic violence charge.

What people get wrong

"I have a right to a polygraph to clear my name." Only a person accused of an enumerated criminal sexual conduct offense has that statutory right.^[2]

"If I pass, the jury will hear about it." Results are inadmissible, whoever they favor.^[1]

"Refusing will be used against me." Evidence that a defendant was unwilling to take a polygraph is barred as well.^[1]

"Nothing from a polygraph can be used." Statements made before, during, or after the examination are not excludable per se.^[3]

For the kinds of evidence that are admissible, start with What evidence is used in a domestic violence case. Opinion testimony from qualified witnesses is covered in Expert witnesses on domestic violence.