When you are accused of a crime it is very important that you leave the evidence alone. You should not destroy, alter, falsify, or conceal any evidence that might have a bearing on your case. It’s also important to avoid offering any exculpatory evidence that you know to be false evidence.
This charge often comes up in drug cases where the defendant is thought to have tried to “flush” the drugs in question as the police made their way into the home. This is an add-on charge, and you can be convicted of this charge even if you are acquitted of the charges that originally led to your arrest.