Dear Mona,

How many Americans serve as jurors in an actual trial in their lifetimes? I’m asking because I was just picked to serve in a jury trial for the third time. Most people I know have never had to sit through a trial as a juror. They may have been called for jury duty, but they were usually dismissed the same day. Am I some sort of an exception?

Andrew, 45, Connecticut

Dear Andrew,

In a 2012 survey, 27 percent of U.S. adults said they had served on a jury at some point in their lives. That survey was conducted by DRI, a membership organization for defense lawyers, and was based on only 1,020 interviews — but it’s the best source I can find to answer your question about lifetime jury service. To get more detailed national numbers, I’m going to have to zoom in on a shorter timeframe.

The National Center for State Courts (NCSC) estimates that in a given year, 32 million people get summoned for service — though only 8 million of them actually report for jury duty (there are lots of reasons for that difference, including the 4 million summonses returned by the post office marked as undeliverable and the 3 million people who fail to appear). It’s estimated that only 1.5 million people are eventually selected to serve on a jury in a state court each year. Those numbers, the most recent available, come from a 2007 survey conducted by the NCSC.

NCSC analyst Greg Hurley explained to me that while federal courts are under a unified system that makes data collection pretty easy, “state courts are a different bird.” Their sheer number (there are more than 3,000 U.S. counties, and almost every one has a court), as well as their differing practices in jury selection, makes it impossible to collect state-court-level data without time-consuming and expensive surveys. So, to get more recent and more detailed data, I’m going to have to look at the federal courts. Which is a shame because that data represents a small fraction of all U.S. adults’ experiences of jury service.

Last year, almost 64,000 people were selected for federal jury service in the U.S. — that’s only 0.03 percent of the adult population. If you want to understand the probability of getting selected, you have to use the adult population as your baseline because you have to be at least 18 to serve on a U.S. jury. That’s not the only condition for jury service, though — in fact, the pool of people from which juries can be drawn is considerably smaller than the 238 million adults in America.

To be legally qualified for federal jury service, you also have to be a U.S. citizen, which, according to 2013 estimates from the Census Bureau, brings the number of potential federal jurors down to 218 million adults. Another condition for serving is that, with some exceptions, you can’t have been convicted of a felony — which as of 2010 ruled out about 6 million adults, taking us to 212 million.

And, if your English isn’t proficient enough to satisfactorily complete the juror qualification form, you can’t serve, either — that could affect some of the nearly one in 10 working-age U.S. adults who in 2012 were considered “limited English proficient.”

There are even more criteria to be legally qualified for federal jury service than we can get into here — and they’re even more complex to quantify. So I don’t know the number of people who are eligible to be jurors in the U.S., and without that number, I can’t really give you an accurate probability about your chances of getting selected. Please try to keep that in mind as you read on.

Let’s go back for a minute to the number of people who were selected for federal jury service last year. In the 12 months through September 2014, 48,877 adults served in trial juries, according to caseload statistics from the U.S. federal court system. Another estimated 14,879 adults served in grand juries over that period. In the case of grand juries, the federal courts track only the number of grand juries (763 last year) and the number of times jurors report to them (164,856 last year — meaning one juror that attends on five days is counted five times). So to figure out the number of jurors that represents, I had to use an estimate (a federal courts spokeswoman told me in an email, “We know it’s in the range of 12,208-17,549,” so I took the midpoint of that range).

That’s your first clue that those two types of jury are a little different. A trial jury, also known as a petit jury, tends to be smaller than a grand jury. Its purpose is slightly different, too — a trial jury reaches a verdict (either in favor of plaintiff/defendant in a civil case or guilty/not guilty in a criminal case), and a grand jury is tasked with determining whether there is “probable cause” to believe a person has committed a crime. Technically, adding the number of adults who have served on a trial jury and a grand jury is a little simplistic; it’s possible that someone may have served as a juror twice in a given year, but it’s highly improbable. The random selection process makes it unlikely that someone will get called to serve twice — and once you’ve served, the Jury Act also excuses you from federal jury service for the next two years (exception: if you served on a petit trial that lasted less than a month).

Selection is just one part of this story — a whole lot of Americans get called for duty but never witness a trial (people on grand juries don’t witness a trial, so we’ll exclude them here).

In the 12 months through September 2014, a total of 218,203 U.S. citizens were present for federal trial jury selection — but only 22.4 percent of those adults were eventually selected, according to the U.S. courts. Overall then, 0.09 percent of U.S. adults were called to serve on trial juries in 2014, and 0.02 percent ended up serving.

The federal courts are trying to change those numbers, because inviting a potential jury member and then not selecting her is costly. In the federal system, the courts are required to pay prospective jurors $40 a day, whether they’re selected to serve or not. That means wasted juror time costs the federal judiciary hundreds of thousands of dollars each year.

Selection rates don’t just reflect everything about how the court system works — human behavior is a factor, and some people try to maximize or minimize their chances of getting selected to serve once they’re called upon. I won’t even attempt to quantify that for you, though, Andrew — to do so would require data that could be affected by people’s willingness to tell the truth about what they do when they get called for jury duty, not to mention their ability to be aware of their own biases and behavior.

And once you get past the top-line facts about the number of people called and selected, the reality of who serves on a jury is infinitely more complicated. That’s because the details of a case are of huge importance to the attorneys selecting the jury. This interactive graphic by The New York Times does a good job of illustrating how prosecutors and defense lawyers pick jurors. It’s based on a hypothetical scenario where the plaintiff is a woman in her 60s who says she lost money because her investments were mismanaged. As well as occupation, age and income level, the factors that affect a prospective juror’s chances of being selected for that trial include whether she has close family or friends in the finance industry and even whether she likes crossword puzzles. All of which is yet further evidence that understanding the probability of being selected for jury duty involves a lot of variables.

The numbers do show that the chances of getting called in the past 12 months are pretty low. And the fact that you’ve served on three juries now does seem pretty remarkable, Andrew. But maybe you’re the perfect juror. I don’t know anything about you other than your age, state and gender — let alone details about the trials you’ve served on. All those variables could either make it more surprising that you’ve served three times — or a lot less surprising.

Hope the numbers help,

Mona

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