In most situations, copying a key without the owner’s permission is not illegal. No federal statute bans the duplication of ordinary house, car, or office keys, and no state has a general law against it either. The legal risk sits in a few narrower places: keys protected by specific federal statutes, patented restricted keyways, contracts that forbid duplication, and above all what you do with the copy once you have it. Cutting the key is almost always lawful. Using it to enter a space you’re not authorized to be in is where criminal charges begin.
Copying an Ordinary Key Is Not a Crime
There is no federal criminal statute that prohibits copying a regular house key, car key, or office key, and no state has a blanket ban. A locksmith or an automated kiosk at a hardware store can copy your key without asking who owns the lock it fits, and neither of you is breaking the law.1Medeco. The Myth of Do Not Duplicate
The key blank is just a piece of metal until it’s used. If someone finds a key on the sidewalk, copies it, and lets themselves into a stranger’s apartment, the crime is trespass or burglary. It isn’t key duplication. That distinction shapes everything else on this page: the question is almost never “was the copy legal” but “was the entry authorized.”
“Do Not Duplicate” Stamps Have No Legal Force
Keys stamped “Do Not Duplicate” are widely misunderstood. The stamp is not backed by any criminal statute, and there is no penalty for ignoring it. A locksmith can legally copy a key bearing that inscription, and most will do so without hesitation.1Medeco. The Myth of Do Not Duplicate
The Associated Locksmiths of America has stated that orders for “Do Not Duplicate” keys should be handled the same way as any unrestricted key, and that the stamp provides a false sense of security. An honest locksmith might ask a few questions. A self-service kiosk won’t ask anything. If a building manager has told you a stamped key can’t be copied, the technical reality is that any hardware-store machine can duplicate it in under a minute.
Restricted Keyways Are Protected by Patent Law
A restricted keyway is a different category. Manufacturers like Medeco, Mul-T-Lock, and Abloy design key profiles with patented geometries that ordinary machines can’t reproduce, and the blanks aren’t sold to the public. Only authorized locksmiths can order them from the manufacturer, and they’re required to verify authorization before cutting a copy.
Duplicating a patented key blank without authorization violates federal patent law. That exposes both the person requesting the copy and any locksmith who knowingly cuts a restricted blank to civil lawsuits for damages and injunctive relief, with enhanced damages possible for willful infringement. These are civil consequences, not criminal, but they are real and enforceable. If a property owner wants genuine control over duplication, a patented keyway is the only approach that holds up.
Federally Protected Keys Carry Prison Time
Two federal statutes create sharp exceptions to the general rule, and both carry serious penalties.
Postal and Mailbox Keys
Under 18 U.S.C. § 1704, it is a federal crime to forge, counterfeit, or knowingly make any key suited to a lock used by the U.S. Postal Service on mail, mailbags, lock boxes, or other authorized receptacles. The statute also criminalizes possessing such a key with intent to use, sell, or dispose of it improperly. A conviction carries a fine, up to ten years in federal prison, or both.2Office of the Law Revision Counsel. 18 U.S. Code 1704 – Keys or Locks Stolen or Reproduced
That includes the arrow-style keys that open cluster mailboxes in apartment complexes when they’re owned by USPS. Making a spare for a spouse is still an offense if the key is a USPS key. The Postal Service controls those keys, and intent to help a family member does not change the analysis.
Department of Defense Keys
A parallel statute, 18 U.S.C. § 1386, protects keys and keyways adopted by any branch of the Department of Defense for securing conventional weapons, ammunition, special weapons, or classified information and equipment. Forging, counterfeiting, or knowingly making such a key without authorization is illegal, as is possessing one with intent to use, sell, or improperly dispose of it. The penalty mirrors the postal statute: a fine, up to ten years in prison, or both.3Office of the Law Revision Counsel. 18 U.S. Code 1386 – Keys and Keyways Used in Security Applications by the Department of Defense
Electronic Fobs and Access Cards
Cloning an RFID badge or programming a key fob to mimic an authorized device doesn’t involve cutting metal, but it can still bring legal consequences. The Computer Fraud and Abuse Act makes it a federal crime to intentionally access a protected computer without authorization. Electronic access systems that rely on networked computers to authenticate credentials can bring the CFAA into play. Penalties range from up to one year in prison for basic unauthorized access to ten years for offenses committed for financial gain or in furtherance of another crime, with repeat offenders facing up to twenty years.4Office of the Law Revision Counsel. 18 U.S. Code 1030 – Fraud and Related Activity in Connection with Computers
Whether cloning a specific badge counts as “accessing a protected computer” depends on the system architecture and how courts in a given jurisdiction read the statute. The safer assumption is that cloning electronic credentials for a building you’re not authorized to enter creates real legal exposure, even if the precise charge varies.
Using a Copied Key Is Where Criminal Charges Attach
Duplicating a standard key won’t lead to criminal charges on its own. Using it to enter property without permission can. This is where most of the real legal risk lives.
If someone uses a copied key to enter a building and commit a theft or felony inside, that is burglary. The FBI’s Uniform Crime Reporting standards explicitly include the use of unauthorized keys as a method of forcible entry, placing it in the same category as picking locks or breaking windows.5Justia. Uniform Crime Reporting Handbook – Burglary Breaking or Entering Burglary is a felony in every state, and penalties commonly include years of imprisonment.
Even without a theft, entering someone’s property with a copied key can support trespass charges. Some states also have “possession of burglar’s tools” statutes that may apply if a person is caught carrying an unauthorized key together with evidence of criminal intent. The key alone probably isn’t enough for a tools charge, but combined with other circumstances it adds weight to a prosecution. The legal system does not care much about the copying itself. It cares intensely about unauthorized entry, and a copied key is strong evidence that the entry was deliberate.
Lease and Employment Contracts Can Still Bind You
Even where copying a standard key is legal, a contract can make it costly. Lease agreements commonly include clauses prohibiting tenants from duplicating keys without the landlord’s written approval. Violating that clause is not a crime, but it is a lease violation, and depending on the language the consequences range from fines to eviction proceedings.
Employment contracts work similarly. Employers in secure environments often include key control provisions that specify who can authorize duplication, require logging of all copies, and impose disciplinary consequences for violations. In industries handling sensitive information or valuable inventory, unauthorized duplication can be grounds for immediate termination.
Courts enforce these provisions. If a lease requires written permission and a tenant copies the key anyway, the argument that key duplication is technically legal rarely helps. The contract creates an obligation that exists independently of criminal law.
Civil Damages When a Copy Causes Harm
When unauthorized duplication causes actual harm, the person or business affected can pursue civil claims. The most common is breach of contract: a landlord sues a tenant who violated a no-duplication clause, or an employer seeks damages from a former employee who copied facility keys before leaving.
Damages typically cover the cost of restoring security. Rekeying a single residential cylinder runs roughly $20 to $75, but commercial properties with dozens of access points can face bills in the thousands. Courts can also order injunctive relief, requiring the offending party to return all unauthorized copies and pay for a full rekey. If the copy leads to an actual intrusion, claims can expand to include invasion of privacy or trespass, and the financial exposure grows quickly once attorney fees and possible punitive damages enter the picture.