Subornation of perjury is a fancy legal name for inducing someone else to lie under oath, and then that person, when called as a witness, goes through with the lie. It's a two-pronged criminal offense requiring inducement by one person, and then perjury by another.
The necessary level of involvement in inducing the witness to lie can vary, depending on the status of the inducer. Sometimes it's as simple as trying to persuade the witness to tell the lie. Sometimes, such as in the case of a lawyer, it can be even simpler; just knowing the witness is going to lie will satisfy the inducement prong. The level of inducement need not be some overt threat. It can be gentle or even implied persuasion.
There are some defenses to the charge, but if it sticks, federal subornation of perjury is punishable by fines up to $2,000 as well as up to five years in prison; state charges generally carry a year or less in prison. Things can get dicey if the subornation of perjury happens during a criminal trial. As you can imagine, that person becomes an accessory to the crime after the fact, which is an entirely different charge onto itself with potentially major punishments.
Charge Requires Proving the Underlying Perjury
Subornation of perjury is not easy to prove, since both the perjury and the inducement must both be proved beyond a shadow of a doubt in a unanimous decision. In U.S. Court of Appeals Chief Justice Richard A. Posner's book, An Affair of State, Posner discusses how difficult proving this crime can be, using President Clinton's words and actions in the Monica Lewinsky case. Posner claimed that though it was clear beyond a reasonable doubt, on the basis of public record, that Clinton was suborning perjury with a few witnesses, "these offenses cannot be proved with the degree of confidence required for a criminal conviction."
For this subornation charge to stick, a prosecutor must prove the witness lied under oath. Perjury convictions are rare because it is very difficult to undeniably prove someone intentionally lied under oath, and that the lie was important to the outcome of the case. According to Jim Cole, an experienced Washington integrity lawyer, "when you try a perjury case, you are splitting legal hairs. They are very technical cases. It comes down to what the person said, what they understood themselves to be saying, and what they understood the question to be."
It Also Requires Proving Inducement
Another reason subornation of perjury is difficult to prove is because of the inducement element. For instance, some believe that President Trump should be charged with subornation of perjury, alleging that Trump told his attorney, Michael Cohen, to lie to Congress about the status of the Trump Tower project in Moscow. Cohen has already been found guilty of perjury. But for this charge to stick against Trump, the inducement must be proven.
In any subornation of perjury case, a prosecutor will have to prove that the suspect put in some effort to try to get the witness to lie, or to perjure. That's not always so easy, given the rules of evidence permissible in a trial. Also the pressure to lie could have been erroneously implied by the witness. For instance, if the evidence used to prove that Jane was inducing a witness to lie was that she was winking her left eye when having eye contact with the witness, Jane may say that she was winking because she had an eyelash in her eye. If there is no irrefutable proof that the suspect was inducing pressure on the witness, there is no crime.
If you are being charged with subornation of perjury, contact a local criminal defense attorney. The charge can be very serious, especially if it leads to accessory charges as well.