The Short Version
This claim is accurate. Under U.S. law, Miranda warnings are required before custodial interrogation, not as a condition of a lawful arrest. If police fail to read Miranda rights, the arrest itself remains valid as long as it was supported by probable cause. The consequence of a Miranda violation is typically suppression of unwarned statements, not invalidation of the arrest. However, suppression of key evidence can sometimes weaken the prosecution's case and may indirectly lead to reduced charges or dismissal.