Why are the Miranda Rights are "Why are the Miranda Rights are "You have the right to remain silent. Anything you say can and will be used against you in a court of law?' Shouldn't it be can and MAY be used against you in a court of law? Do they have to use what they say against you?
DUI / DWI Attorney
The difference between the two words is notable, but I think they use the word "will" to get the person's attention and to give them fair warning to be careful in what they say. If the word "may" was used instead, the person might think they could say some things without them being used against them later.
Criminal Defense Attorney
While a prosecutor may or may not use the statement of a person questioned by police in a trial, the term "will" is presumably meant to provide a stonger warning to the person who is "in custody" being questioned. This helps the police later, if the person is foolish enough to talk to them anyway, even after the more strongly worded warning.
First and foremost, that particular choice of words is drawn from Chief Justice Warren's opinion for the majority in the U.S. Supreme Court's decision in Miranda v. Arizona. In that opinion he used several formulations, including "can be used," will be used," and "can and will be used." So, the current use of "can and will" seems to be the one option that covers all the constitutional requirements as determined by the Supreme Court. Also, Warren was a former prosecutor and may have chosen that particular phrasing based on his personal knowledge of the importance of leaving little doubt in a suspect's mind that his or her statements to police are often highly detrimental to his or her case.