One of the questions I get asked frequently is whether or not someone who is accused of a felony should testify on their own behalf during the grand jury proceedings. First, there is no constitutional right to testify in the grand jury on your own behalf. What that means is, unlike trial where it is your choice, your attorney can choose to not have you testify in the grand jury even if you have told the judge and your lawyer that you wish to testify. Yes you read that correctly, the person who is facing substantial jail time does not get to choose whether or not to testify in the grand jury (although most attorneys respect the wishes of their clients).
Testifying before a grand jury is a very risky proposition because the prosecution has many advantages. For example, during a trial, a defendant makes the decision of whether to testify after having heard all of the evidence against him. He can address any issues that the prosecution has raised through their witnesses. In theory, a defendant can alter or tailor his testimony around the scientific evidence or indisputable proof. At the grand jury phase, a defendant has no idea what the grand jury knows or has heard. Whatever statement a defendant makes is sworn to and on record; so if evidence is discovered later on that refutes or contradicts a defendants testimony, he is stuck with what he has already said and this could be very damaging. Moreover, a defendant who testifies unsuccessfully at the grand jury has handed the prosecutor a decisive advantage at trial as the prosecutor now knows the complete defense strategy and tesimony.
Also, there is no judge during the grand jury proceedings. The prosecutor controls what the grand jury sees and hears. I have seen many prosecutors unfairly limit the testimony of a defendant to what they feel is relevant and unfortunately a defense attorney is very limited on how they can combat this. Moreover, prosecutors have much more leeway in asking defendants about their prior criminal history in the grand jury than at trial. At trial, defense lawyers can get a ruling from the judge that prohibits or severely limits the prosecutors ability to discredit the defendant because of prior trouble with the law.
Lastly, the function of the grand jury is not to decide guilt or innocence. They are merely determining whether there is probable cause to believe that a crime was committed by defendant; a much smaller burden than beyond a reasonable doubt. In law school, we were taught an old saying that a prosecutor can indict a "ham sandwich". In other words, there isn't much that a grand jury won't indict.
All this being said, there are times when a defendant should testify before the grand jury; however, those times are usually dictated by the specific facts of the defense. This can only be determined by someone who is familiar with the facts of the State's case and the accused's defense. The best advice would be to sit down and discuss the facts of what happened with an experienced criminal attorney who can better advise you.
Legal disclaimer: All answers are for information purposes only. Answering this question or any future questions does not form any attorney-client relationship. Be mindful, that answers are limited by the limited facts presented by the questioner and are not meant to take the place of competent legal advice by an attorney fully informed of all the facts surrounding your case. However, be aware that nothing posted in a public forum such as this can be deemed confidential or privileged communication. For a privileged private consultation, contact me at 212-385-8600 or via my website www.reasonabledoubtny.com