One of the most common complaints we receive as criminal defense attorneys is: "I wasn't read my rights."
The majority of the public is under the impression that if their rights (you have the right to remain silent . . . etc) are not read after someone is arrested the police did something wrong and/or the charges must be dismissed. This is simply not the case. The only time that Miranda rights must be read to an individual arrested for a crime is if the police want to question the arrested individual and then seek to use the answers against the person in the criminal prosecution. Miranda warnings are only required when: (1) a suspect is in custody; and (2) there is an interrogation.
"Custody" occurs when an individual is taken into custody (formally arrested) or otherwise deprived of his freedom in any way. This is an objective test. The only relevant inquiry is how a reasonable person in the suspect's position would have understood his situation. Iowa has adopted a four-factor test as guidance in making this determination. These factors include: (1) the language used to summon the individual; (2) the purpose, place, and manner of interrogation; (3) the extent to which the defendant is confronted with evidence of his guilt; and (4) whether the defendant is free to leave the place of questioning.
The term interrogation under Miranda refers not only to express questioning, but also to any words or actions on the part of the police that the police should know are reasonably likely to elicit an incriminating response from the suspect. The reasonably likely to elicit an incriminating response from the suspect language focuses primarily upon the perceptions of the suspect, rather than the intent of the police. A practice that the police should know is reasonably likely to evoke an incriminating response from a suspect thus amounts to interrogation.
If someone is in custody and is interrogated without the reading of their Miranda rights, the charge still does not get dismissed. Rather, the only remedy is that the suspects answers to the questions of police officers get suppressed or thrown out of court. However, if the defendant elects to take the stand in his/her own defense, the prosecution is allowed to cross-examine the defendant with statements made to the police even if Miranda was violated. The reasoning behind this rule is that no witness is ever given the "license to commit perjury." The Court's wont throw out a confession saying you did it and then permit you to take the stand and say you didn't do it without the prosecution being able to question you about your prior statements. This is why anybody under investigation for any criminal activity is always better off not saying anything. Remember, prisons are full of people who attempted to talk their way out of being arrested or spending a couple of nights in jail.