Earlier quoted context omitted.
In the US, at minimum you’re lying to a federal agent. Never a good idea.
I don't know the legal implications, but if the duress password unlocks your device and simply deletes a directory or two, and the officer only asked you to unlock your device (without a warrant, by the way), how is that lying?
> Whoever knowingly alters, destroys, mutilates, conceals, covers up, falsifies, or makes a false entry in any record, document, or tangible object with the intent to impede, obstruct, or influence the investigation or proper administration of any matter within the jurisdiction of any department or agency of the United States or any case filed under title 11, or in relation to or contemplation of any such matter or case, shall be fined under this title, imprisoned not more than 20 years, or both.