SANFORD, Fla. -

Jurors in the George Zimmerman trial  are set to find out that Trayvon Martin had marijuana in his system the day he died. The toxicology report could be introduced into evidence, the judge ruled Monday.

Letting jurors know about Trayvon testing positive for “minimal” levels of THC -- the active ingredient in marijuana -- would be “unduly prejudicial,” prosecutor John Guy said Monday. Defense attorney Don West argued that the medical examiner’s testimony increased the toxicology report finding's relevance.

"Now his testimony is 'Yes, there was sufficient THC in Mr. Martin's system that it would have had some effect,'" West said.

Judge Debra Nelson had banned mentions of the toxicology report in the attorneys' opening statements, but said they could present testimony about the effects of THC.

In November, medical examiner Shiping Bao said the THC traces did not have any effect on Trayvon’s behavior. Bao changed his testimony Friday.

"Marijuana could have no effect or some effect" on Trayvon’s behavior, Bao said during his testimony for the prosecution Friday.

Trayvon was in Sanford, Fla. the day of the fatal shooting, after he was suspended from Dr Michael M. Krop Senior High School in Miami.  School officials reportedly found a small plastic bag suspected of containing marijuana in his book bag. No charges were filed.

In Zimmerman’s call to police Feb. 26, 2012, the crime watch volunteer told a 911 dispatcher Trayvon appeared to be “on drugs or something.” West said the defense was ready to present an expert witness as early as Tuesday.

Some legal experts believe the toxicology report will have a major impact in the jurors' perspective.

"The toxicology report is character evidence," Orlando criminal defense attorney Lyle Mazin said.