Many defendants lack the financial means to post their own bail. To secure release, they may contract a commercial bond agent to act as surety for the bond. The agent posts bail after collecting a nonrefundable fee (typically 10 to 20 percent) from the defendant or family or friends. Assuming the defendant does not have money to give the agent as security, an agent will obtain other collateral, such as jewelry, securities, or electronics. In return, the bail bond agent agrees to pay the remaining amount to the court if the defendant fails to appear.

There are approximately 14,000 bond agents in the U.S. Most states require a bond agent to be licensed. However, the license typically is not specifically for bonding purpose, but for property and casualty insurance. To obtain the license, the applicant must meet certain educational requirements. This allows a potential bail bond agent to be appointed by an insurance company to write bail bonds. The defendant pays the agent for writing the bond. In turn, the agent pays the insurance company a premium. The bail agent is responsible for bond payment in the event a defendant fails to appear and cannot be located.

To ensure a defendant's appearance in court, a bail bond agent may require a defendant to check in by telephone or in person, or may require the defendant to be monitored in some other way. In extreme cases, a bail bondsperson may place a guard on the defendant. A bail bond agent is not obligated to post bail if the agent concludes a defendant is not likely to fulfill the obligations of the bond.

Illinois, Kentucky, Oregon and Wisconsin have outlawed the practice of posting bond for profit. In those jurisdictions, a defendant may be allowed to satisfy the requirements of the bond by posting 10 percent of the bail amount with the court. Some other jurisdictions, such as Maine and Nebraska, allow commercial bail on a limited basis.