Even though you know that serving on a jury is your civic duty, it's nobody's favorite thing to rush down to the courthouse at dawn and wait. And wait. And perhaps never be needed or selected. In order to minimize this, some courts use the standby system. This is a method of ensuring that enough people are available for scheduled trials without bringing them all to the jury room to wait.
TL;DR (Too Long; Didn't Read)
The standby system of jury duty requires that people called to serve check in by phone rather than showing up at the courthouse in the morning. They only have to go in if and when they are needed.
An Inconvenient Necessity
For many people, jury duty is an inconvenient necessity, or at least it used to be. Obviously, being tried by a jury of one's peers is a right in our democracy, and to make that work, people from all walks of life must serve. But you have to miss work, travel to the courthouse across town, arrive on time – then wait. Although your employer must allow you to serve and continue to pay you, it's a nuisance, especially if you are never selected to hear at case.
The standby system was intended to ride to the rescue by eliminating some of the inconvenience. If you are called to jury duty, you check in by telephone to find out your instructions. For example, if you are called to serve on Monday morning at 8 a.m., you can call Friday and listen to the recorded message telling you whether and when to show up, or when to call back. You may be told to report Monday at 8:00 a.m., to check back at noon to see if you are needed for the afternoon, or simply to call in later to see if you should show up Tuesday. In the meanwhile, you can report to work. You must keep checking back until you are either told to report to the courthouse or that your service is complete without having to report.
Variations on a Theme
Not all standby rules are the same, so if you are called for jury duty, read up on how it works in your jurisdiction. It varies even among counties in the same state. For example, in some counties in California, like San Diego, every juror begins service on standby status. In other counties, like San Francisco, each potential juror is assigned to a group, and some groups of jurors are on standby and some are not. Those that are not must show up at the courthouse. In Cook County, Illinois, your jury duty notice will specify if you are on standby. If you are, you call in. If the notice does not mention standby, you must show up at the court.
Ignoring the Summons
It's neither very responsible nor very wise to ignore a jury notice. The trial court system of the United States depends on people appearing when summoned as potential jurors. And those who ignore the notice and fail to respond or appear will probably regret it. Usually, the judge in charge issues a bench warrant for your arrest. That means that if you are stopped by the police for some small infraction, like a broken brake light, you will be arrested and taken before the court.