Shouldthere be no deal, dozens of prospective jurors will file into the federal courthouse and Judge T. P. Jackson's courtroom tomorrow to begin the trial of Mayor Marion Barry. They may not know it, but already the lawyers in the case -- the prosecutors and the defense team -- have tried to size them up, compare them to some ideal profile each has, and have developed some way of determining who will be left to hear this case. A great deal of trial work remains a mystery to the general public (and to a lot of lawyers). One of the areas most misunderstood, however, is jury selection.

To begin with, the phrase "picking a jury," is a misnomer. Attorneys do not and, actually, cannot "pick" the jury they want. Instead, a random number of people will be called to a jury box or designated on a jury list, and the attorneys, based on the question that they have asked and feelings that they have, then have a certain number (usually government six; defense 10) of strikes to take out of the box or off of the list those people that they do not want. So, rather than selecting a jury, attorneys actually are discarding non-jurors.

Similarly, the concept of selecting a "fair and impartial jury" exists more in textbooks than in practice. It is more accurate to say the government tries to strike from the prospective jury those who appear to them to lean to the defense; and the defense does the same for those perceived to be pro-government. The theory is that the active government will remove those leaning to the defendant, the on-their-toes defense will strike those for the government, and the rest will be neutral. As with most trial events, the theory is easier than the execution. Figuring out who is pro-government or pro-defense is far from a science. This process of sizing up the potential jurors, especially important in any high-profile case, such as that of Mayor Barry's, is scheduled to take the better part of two weeks of written questionnaires, individual interviews and questions asked in open court to each would-be panelist.

If a defendant has a reasonable defense, conventional trial wisdom is that he or she will want a juror who will think carefully about the evidence. Where the defense to a bank fraud case depends on a careful sifting of 100,000 documents, an attorney might seek educated jurors with business backgrounds, who will look dispassionately at the trial evidence. If on the other hand there is virtually no defense, such as a bank robbery with videotape of the defendant, 10 eyewitnesses and fingerprints, an attorney might seek a big-hearted juror who will acquit for reasons having nothing to do with the evidence, e.g. the defendant grew up in a bad neighborhood; he needed the money for his starving family. This is the well-know "jury nullification."

Recently a juror who sat on a D.C. Superior Court jury that acquitted a defendant of murder charges wrote a letter after the trial stating that she felt bad about the verdict. She explained that the jury reached its verdict not because of the evidence, indeed she said it was in spite of the evidence, because the jury foreman convinced the other jurors that it would be a rotten thing to do to send another black man to jail in a "racist" society.

At first blush, the Barry case looks like the bank robbery. From newspaper reports, the government has the goods on the mayor -- videotape of drug use, testimony of friends who saw him use drugs and chemical reports confirming drugs. With this in mind, there is a lot of conjecture that the mayor's defense is based on "nullification." He and his attorneys will try to appeal to some argument to negate the evidence and cause the jurors to sympathize with the mayor. An obvious possibility is an entrapment defense, which, in effect, attempts to put the government on trial for targeting and setting the mayor up rather than on what the mayor did after he took the bait.

The government, on the other hand, will want jurors who will view the trial evidence and only the trial evidence, leaving outside the courtroom the feelings that led to the murder acquittal described above or sympathy for a mayor who was enticed to a hotel room. Indeed, one government strategy to combat "jury nullification" is to attempt "jury compromise." To do so, a jury is given 10 or 15 different charges in the hope that they will compromise and find some counts for the government and some for the defendant. As jurors are told to disregard what penalties might be given as a result of their verdict, they might not know that finding a defendant guilty of one charge may be as serious as finding him guilty on all 10. One alone will lead to jail, fines, loss of jobs, etc. Initially in the Barry case, the mayor was charged with just one misdemeanor. Later, and even recently, new charges were added so now he has to stand trial on 16 assorted felonies and misdemeanors. No doubt some prosecutor on the case thought "one of these will have to stick."

So "jury nullification" will be up against "jury compromise." The battle is made even more complex by the requirement that verdicts be unanimous. All the mayor has to do is to convince one person that the government was more wrong than he was. While he will not be judged innocent, he will not be found guilty either. Whether an 11-to-1 or 10-to-2 vote for conviction will help Barry stay mayor or allow him to run for reelection is surely a gamble. But it has better odds than a reelection campaign run from Lorton.

So how will U.S. Attorney Jay Stephens or the mayor's attorney Ken Mundy identify the other's best jurors in order to strike them? Some attorneys rely on stereotypes: prosecutors strike young people, because they side with defendants; defense attorneys strike older men, because they are more strict and conservative. Others swear by clothing and body language. One prosecutor's office had a sign in the coffee room that read, "Strike Anyone Wearing A Bandanna, No Matter Where On The Body." Defense attorneys strike potential jurors who slouch and who will not make eye contact (uninterested followers). Like almost all stereotypes and folklore, these "rules" hardly ever hold true in real cases. Attorneys with the experience and ability of those in the Barry case are hardly likely to waste their choices on such worn-out notions.

Instead, those watching jury selection should look for specific questions asked by the attorneys to elicit responses indicating jurors likely to "nullify" or "compromise" the government's case. "Nullifying" jurors might be those who are fiercely antiestablishment, antigovernment or have maverick independent streaks. "Compromisers" are those who hate to make tough choices and who go along with the will of others. To find (and strike) the first, the prosecutors might be asking jurors whether they have ever fought a parking ticket, generally distrust the government or have had to correct an error on their taxes or other forms provided by a government agency. To identify (and remove) the second, the defense may ask who in their family decides on movies or vacations and whether they have a hard time taking sides when they hear two friends argue.

It will be these kinds of questions and answers rather than what dress a person is wearing or how he or she is sitting that will make the difference. You can be sure that an older man, in a three-piece suit, holding a Bible, who says that he challenges his tax returns every year will be as struck from the potential jury by the government as will the defense strike a teenager wearing a bandanna, who states that he just usually does whatever those he hangs around with want to do. The writer teaches criminal law at Georgetown University Law Center.