a.k.a. STFU Donny!
So the detective finally gets enough probable cause to arrest Donny, BUT NOT BECAUSE OF DONNY'S REFUSAL TO ANSWER QUESTIONS! (I will not even touch probable cause, a whole blog could be written on those two words. For now just take probable cause to mean "a reasonable belief that a crime has been committed.") What has to happen next?
When someone is arrested, the law requires that the prisoner is given a Miranda warning. A typical warning is as follows:
You have the right to remain silent. If you give up that right, anything you say can and will be used against you in a court of law. You have the right to an attorney and to have an attorney present during questioning. If you cannot afford an attorney, one will be provided to you at no cost. During any questioning, you may decide at any time to exercise these rights, not answer any questions, or make any statements.
This education of rights is very interesting because it goes against the old adage "ignorance of the law is no excuse." In this case it is an excuse and many confessions and heaps of evidence have been excluded from a prosecution because of a failure to give a Miranda warning.
If Donny is not given a Miranda warning practically nothing he says can be used against him. He can confess, explain where the drugs are, name names, etc., and the law acts like he said nothing. Furthermore if Donny confesses at the behest of police questioning and is then later given his Miranda warnings, the warnings "clean the slate" so to speak. The law still acts like Donny never confessed! This prevents officers from "beating" out a confession that circumvents the Miranda requirement.
If that weren't enough evidence that is gained from information violative of a Miranda warning is often voided as well. Let's say the detective does not give Donny his Miranda warning. Donny explains that Tito is the neighborhood drug lord and he has 20 kilos of cocaine in a nearby dumpster. The detective checks out the dumpster and finds the drugs. This evidence cannot be used against Donny or Tito in this manner. The law makes sure that the Miranda warnings are a gate, not a speed bump to swerve around.
Well now that you, avid reader, have a slight understanding of the Miranda warning's power, what should Donny do when he is given his Miranda warning?
First, a police officer can continue to talk and reasonably question Donny after the Miranda warning is given. Badgering out of the question, but guilt trips, etc. are allowable. This is in the hope that Donny will "waive" his Miranda rights (a very stupid thing to do). If Donny says "I invoke my right of silence," or a similar iteration, no more questioning is allowed for a reasonable period. Furthermore, let's say the first question the detective asks after the Miranda warnings is, "Have you sold drugs?" Donny replies by invoking his right to silence. Nothing can be inferred from this, no evidence can be taken from this, and it is as if the question was never asked for court purposes.
The most powerful thing Donny can do is immediately ask for a lawyer. If this happens the detective can do nothing until Donny sees his attorney. If he even questions Donny whole swaths of evidence may be voided and the detective may get in trouble or set Donny free. The attorney, later showing up, will then counsel Donny to shut up and all will be well.
The reason Donny wants to keep his Miranda rights is bargaining power. If he waives his Miranda rights thinking now that he is being good they will go easy on him, he loses out. If he says nothing until his attorney can plea bargain with the prosecutor, Donny might get a much better deal. Especially in Donny's situation where the cops really want the drug dealers, not the friend of one.
The right of silence when questioned outside a courtroom is not one to simply throw away. Police officers do excellent jobs, but their interrogation powers are very limited. Now, the best deal would be for you, avid reader, to not break the law. But if you do, just shutup.