Terri however was not committing a contract. Her remark was offhand. In no sense did it carry the expectation or weight of a contract. It is mere hearsay.
Hearsay. It's defined in popular culture as something you heard someone else say. The legal definition is a bit different, but let's stick with the popular definition for now.
Lots of people believe that what you heard someone else say isn't admissible in court. That's not true. In the federal court system and Florida's courts (and probably every other state's courts), there is a general rule prohibiting hearsay but dozens of rather broad exceptions to the rule.
The fact that there are exceptions to a rule barring hearsay suggests that some hearsay must be okay, while other hearsay is not. What's the difference? Before considering that, it helps to understand what the problem is with hearsay in the first place.
The common assumption seems to be that hearsay is unreliable -- and should be kept out of court -- because the witness might be lying about what someone else said. Let's put this in Michael/Terri terms. I've heard innumerable people say Michael Schiavo should never have been allowed to testify to what Terri told him because he may have been making it up.
That a witness might be lying about what someone else said is a valid concern, but it's no reason to keep such testimony out of court. After all, what's the difference between Michael testifying that he heard Terri say "don't let me live like that" and Michael testifying that he saw Terri run a red light, or that he saw Terri eat broccoli one night? Nothing, in the sense of Michael's truthfulness. Theoretically, a witness could lie about what someone did just as easily as about what someone said. So, no, we don't make a special case out of hearsay because the witness might not be telling the truth.
We make a special case out of hearsay because, even if the witness really heard the statement, the witness might not reliably convey what the original speaker really meant -- either by mistake or because the original speaker wasn't clear.
A well known example of the problem here can be found in the modern classic My Cousin Vinny. When the officer accuses Billy of shooting the convenience store clerk, Billy responds in disbelief, "I shot the clerk?" Later, when the officer takes the stand and is asked to repeat what Billy said when confronted with the charge, the officer testifies, "He said, 'I shot the clerk.'" Subtle difference, but a huge one. The officer got the words right but the meaning wrong. You'd want to talk to Billy to be sure you understood what he really meant.
So the trouble with hearsay isn't that the witness might not be telling the truth about what someone else said. The witness's truthfulness can be an issue no matter what the witness claims to have heard or seen or done. The trouble with hearsay is that without the "someone else" there to examine, it can be very difficult to determine the reliability of the witness's interpretation of the other person's words.
If you look at the exceptions to the hearsay rule -- and there are dozens -- you'll notice that lots of them concern situations where we can be fairly sure of what the speaker meant. I may discuss this in more detail at a later time.
The next time you hear someone say Michael shouldn't have been allowed to testify to what Terri told him, ask if the person is being critical of Michael's ability to convey what Terri really meant or if the person just doubts Michael told the truth. If the answer is that we can't be sure what Terri's words meant, then at least the person's in the ballpark with the problems of hearsay (though it was still admissible...). If the answer is that Michael may have been lying, then the person doesn't really understand hearsay in the first place.