When a defendant is arrested, they can give the court money in order to remain free while waiting for their case to get through the court system. This is called bond or bail money.
The obvious discrimination is that a defendant with money can get out of jail while their case is handled, and a poor defendant cannot.
However, the true damage is done in the early court process. Most criminal cases start in general sessions. Here the majority of cases are handled by an agreement with the state. If no agreement is reached, then the case gets bound over to the criminal courts. This process takes about six months to reach the criminal court. If the case is to proceed to trial, then there is another three-six month wait. If a person cannot afford to make their bond, then they will remain in jail this entire time regardless of whether they are guilty or innocent.
The result is that the State has no motivation to consider the circumstances of a crime where a defendant cannot afford their bond. Any offer short of six months is nearly impossible to turn down. An innocent defendant must seriously consider all offers regardless of their merit.
By contrast, any person who is out of jail can ignore poor offers from the state. They can force the state through time consuming hearings and a bind over process at little or no personal cost. This places the state in the position of being highly motivated to settle cases when the defendant is out on bond.
The result is that a defendant who can afford bond will receive better offers than a defendant who cannot. This difference will include pleading to lesser charges and to reduced time. Being convicted of a lesser charge is far less detrimental to future job prospects and to future court proceedings. While jail time almost always results in lost employment, jail fees, and reduced future opportunities. And while someone might find that this is just the cost of committing crime, remember that the only difference in the treatment of the two defendants is that one could afford to bond out of jail and the other could not.