What does demand for preliminary hearing mean

In Colorado, if you are in custody for a Felony (or even out of custody for Class 3 Felonies and Mandatory Sentencing Crimes) you are entitled to have a judicial determination of probable cause. The rules of evidence are typically relaxed at these hearings and all evidence is viewed in the light most favorable to the Prosecution. the "Demand Hearing" is your opportunity to formally request that such a Preliminary Hearing be set (within 30 days if you do not waive that requirement). Good luck!