Over the past few years, you may have heard this term in connection with the Tampa Bay Rays' possible desire to move the baseball stadium (Tropicana Field) from St. Pete to Tampa. It has been reported by Tampa Bay media outlets that Tampa could be "tortiously interfering" with the stadium lease contract (between St. Pete and the Rays for Tropicana Field) by contacting the Rays about a stadium move. You may also hear this term reported in news articles involving business disputes between large corporations.

What, exactly, is the "tortious interference with contracts or business relationships"? Let's assume that a dispute exists involving a contract that is not terminable at will, as opposed to a business relationship or contract that is terminable at will. Under Florida law, a jury deciding a dispute involving a claim for tortious interference with a contract that is not terminable at will would receive the following instructions (or very similar instructions) before rendering its verdict:

The issues for you to decide on the plaintiff's claim against the defendant are whether the defendant intentionally interfered with a contract between the plaintiff and company A; and, if so, whether such interference was a legal cause of damage to the plaintiff.

A person interferes with a contract between two other person’s if he or she induces or otherwise causes one of them to breach or refuse to perform the contract.

Intentional interference with another person's contract is improper. Interference is intentional if the person interfering knows of the contract with which he or she is interfering, knows he or she is interfering, and desires to interfere or knows that interference is substantially certain to occur as a result of his or her action.

If the greater weight of the evidence does not support the plaintiff's claim, then your verdict should be for the defendant. However, if the greater weight of the evidence supports the plaintiff's claim, then your verdict should be for the plaintiff and against the defendant.

If you find for the defendant, you will not consider the matter of damages. But, if you find for the plaintiff, you should award the plaintiff an amount of money that the greater weight of the evidence shows will fairly and adequately compensate the plaintiff for the damage that was caused by the intentional interference.

The foregoing instructions seem rather simple on their face, but there are a few takeaways:

The interference must be intentional. The key here is that there must be proof that the defendant knew of the existing contract and in fact, desires to interfere or knows that interference is substantially certain to occur as a result of his or her action.
The interference must be the legal cause of the damage. Put another way, does the interference directly and in natural and continuous sequence produce or contribute substantially to producing damages, so that it can reasonably be said that, but for the interference with the contract, the damages would not have occurred.
Whether there are concurring or intervening causes of the damages, in addition to the interference. Note that a defendant is not completely excused from the consequences of his or her tortious interference by reason of some other cause concurring in time and contributing to the same damage.
The “greater weight of the evidence” means the more persuasive and convincing force and effect of the entire evidence in the case.

Finally, note the jury may also consider certain other defenses and issues that might be raised by the defendant to support an argument that the interference was proper, such as "justification," "privilege," financial interest, and competition. For example, companies can legitimately compete for business using ordinary and proper business methods. All possible defenses and issues should be fully addressed and analyzed in connection with any tortious interference claim.