“On the advice of counsel” means a person is taking an action—or refusing to take one—because their lawyer told them to do so. We hear this phrase often used during Congressional hearings or police interrogations. But it can also be used as a part of a legal defense strategy to show that a person is acting in good faith.
When a person is charged with a criminal offence, but sought legal advice prior to taking the alleged criminal action, they may be able to argue that they lacked the required criminal intent because they acted in good-faith reliance on legal advice.
Most crimes require the state to prove that the accused acted “knowingly, willfully or with the intent to commit the criminal act.” But if they took the action only after consulting with an attorney and with full disclosure to the attorney, then they can defeat the intent element of the crime. In order to use this defense, the accused must be able to prove four facts:
First: They gave their lawyer a full and honest report of all the facts regarding their planned activity. Second: They asked their lawyer for legal advice on what to do. Third: The lawyer told them the action was legal. Fourth: They acted in good-faith reliance and followed the lawyer’s advice honestly and reasonably.
There are a couple of important consequences to invoking this defense. First, if you say that you took the action “on advice of counsel”, you have effectively waived the attorney-client privilege as to communications between you and the lawyer whose advice you sought. Once the defense is asserted, the prosecution is entitled to obtain communications between the defendant and his attorney – communications that would otherwise be protected as confidential.
When delving into one’s communications with their lawyer, the prosecution will often try and argue that the client did not make a full disclosure, or that he received inconsistent advice, or that the client was selective in his reliance on that advice.
Still, the defense is important because it reflects a core principle of fairness in our criminal justice system. Individuals should not be punished for acting in good-faith reliance on their attorney’s advice, especially when the circumstances involve complex laws.
Oftentimes, during a Congressional hearing we hear an individual refuse to respond to a question “on advice of counsel” and then explain that they are pleading the Fifth. Typically, the response they provide is: “On the advice of counsel, I invoke my fifth amendment privilege against self-incrimination and respectfully decline to answer your question.” But invoking the Fifth Amendment privilege is much different than asserting the “on advice of counsel” defense. It is rooted instead on the constitutional principle that a person cannot be compelled to offer incriminating evidence against themselves. They may, for example, on the advice of their defense lawyer, refuse to take the witness stand in a criminal trial. Their failure to testify cannot be used against them when the jury deliberates over their guilt or innocence.
—Larry L. Crain – www.crainlaw.legal

