When you're being questioned by the police anything you say can be held against you. Since under our justice system, we’re considered innocent until proven guilty, the prosecution must present evidence of our guilt in order to convict us. A confession or other damaging admission is usually considered very good evidence of guilt. Problems arise when being questioned by the police because you could be nervous or feel pressured, and maybe say the wrong thing, perhaps mistakenly confessed to a crime that you didn't even commit, or make some other statement that puts your rights in jeopardy. This is why it's important to invoke your constitutional right to remain silent and have an attorney present during questioning. Even if the police initially inform you of your Miranda Right to remain silent, if you later talk to the police anyway even hours later, you can be held to have waived your constitutional rights. If you're ever questioned by the police you don't have to say anything you can simply remain silent the whole time or you can ask to speak to a lawyer first. Even if you have to repeatedly ask for a lawyer, it's better than saying something in error and harming your legal rights.