Anyone who's ever seen much American film or television has heard some variation of the following sentences countless times:
You have the right to remain silent. If you choose to give up that right, anything you say can and will be used against you in a court of law.
And the phrase "can and will" can be seen in other contexts as well. My issue with this is not the "can" part, but the "will" part. "Can" implies that anything you say may be used against you in court, but "will" asserts that it is a certainty. The person being arrested could obviously say any number of things that would not be of any use in a case against them, so it's not true to say that anything they say will be used, only that it can be.
Does Hollywood have it wrong? I looked around to see what the official text of the Miranda warning is, and it seems there isn't any – it varies from one jurisdiction to the next, but the Hollywood version is always pretty much the same. (The Miranda rights are universal, but the actual words to be spoken by the arresting officer are not mandated so long as the rights are properly delineated.)
And more to the point, is this phrase just being incorrectly used in these (and other) cases? Does "can and will" maybe bear more legal weight than simply "can"? Or could the officer leave out the "and will" part and consider the Miranda warning just as properly given without it?
Best Answer
The will in can and will is not the epistemic ("predicted/expected future") will, but rather the deontic ("be willing to") will, the one that shows up in hypothetical clauses (where you were probably told in school that you "can't use the future tense").
The first will is deontic only; the second could be either deontic or epistemic.
(Ambiguity, too! Aren't modals fun?)
That means that, since the can part means be able and the will part means be willing, the whole phrase can and will is just a verbing of able and willing. And both parts are necessary.
Modals are tricky that way; every modal auxiliary has an epistemic and a deontic sense, and you always have to figure out which one is intended, because they're not marked and each reading of each modal has its own unique grammar.