What type of challenges do juror expectations and misconceptions bring to today’s courtroom?
Myth: All scientific evidence can be presented in the courtroom.
Fact: To be admissible in court, evidence generally has to meet one of two standards, commonly known as “Frye” and “Daubert” (referring to the two landmark rulings by these names). The Frye standard takes into account the general acceptance of the analytical technique by the forensic community; the Daubert standard relies on the expert witness’ qualifications, and the principles and methods underlying the forensic technique. [Source: Focus Group on Scientific and Forensic Evidence in the Courtroom, NIJ, 2007.] .pdf download
46% of jurors expect to see some kind of scientific evidence in every criminal case. 
Pinellas Circuit Judge, Sixth Judicial Circuit Biography »
The Honorable Thane B. Covert began his tenure as a Circuit Judge of the Sixth Judicial Circuit on January 3, 2006. He currently presides over felony cases in Pinellas County, criminal division. He was appointed by Governor Jeb Bush to fill a new Judgeship created by the 2005 legislature.
Immediately prior to being appointed to the bench, Judge Covert was an Assistant State Attorney, Lead Trial Attorney, in the State Attorneys Office of the Sixth Judicial Circuit of Florida. He was an Assistant State Attorney for eighteen and one half years and was previously assigned to the career criminal unit and as a county court supervisor. He was involved in over 100 jury trials and as a Lead Trial Attorney supervised 5 felony Assistant State Attorneys who managed a caseload of over 1000 cases monthly.