Not all keys can be duplicated legally, and some restrictions apply based on the key type, location, and intended use. Understanding these limits protects you from legal trouble and helps you find a locksmith or key-cutting service that operates above board.
Know Your Key Type
The first step is identifying what kind of key you're trying to duplicate. Standard residential or office keys made from brass or aluminum have virtually no restriction—any hardware store or locksmith can cut them, and you'll pay $2–$5 per copy. The legal grey area starts with restricted keys.
Restricted keys come in several categories. Master keys, change keys, and keys marked "Do Not Duplicate" (or stamped "DND") sit in a legal limbo. A locksmith can technically duplicate them if you own the lock or property, but many choose not to without proof of ownership or authorization from the property owner. This is a liability issue for the service provider, not necessarily a criminal one for you—but some states have explicit laws against duplication without consent.
Patented and Proprietary Keys
Certain manufacturers—Medeco, ASSA ABLOY, Mul-T-Lock, and Schlage are common examples—design keys with patents or security features that restrict duplication. These keys are intentionally harder to copy, either because the blanks are controlled or the cutting specifications are proprietary.
If you try to duplicate a patented key at a standard hardware store or general locksmith, you'll likely hit a wall. The blank won't be in their inventory, or they'll decline on principle. Your legitimate options are:
- Contact the lock manufacturer directly and request a key copy (costs $15–$40 depending on the brand)
- Visit an authorized dealer for that brand
- Hire a high-security locksmith specializing in restricted-key systems (expect $25–$60 per key)
- Provide proof of ownership if buying from a locksmith (receipt, registration, or property deed)
Legal Issues by Location
A handful of U.S. states and some international jurisdictions have laws against duplicating certain key types without explicit permission from the property owner. California, for instance, has gray-zone language around duplicating keys to rental properties or shared spaces. New York and Texas focus enforcement on keys that serve locks used in criminal activity, not the duplication itself.
Before you proceed, check your state's locksmith licensing board website or ask your locksmith directly. A reputable key-cutting service will ask about the key's use and may require a photo ID or written authorization if it's a restricted or commercial key.
Government and High-Security Keys
Keys for government buildings, military facilities, or sensitive infrastructure cannot be duplicated by anyone without federal clearance. This includes keys to courthouses, federal offices, and certain commercial security systems. Attempting to duplicate these keys is a federal crime.
Similarly, keys marked with security levels (often color-coded or stamped with manufacturer warnings) should only be copied by locksmiths certified to handle that security tier. These services cost $40–$150+ per key, but they're the only legal route.
What to Do Before Requesting a Duplicate
Before you walk into a locksmith or hardware store, take these steps:
- Check the key itself. Look for "Do Not Duplicate," patent numbers, brand names, or security markings.
- Verify you have the right to copy it. If it's not your personal house key, confirm you own the lock or have permission from the owner.
- Ask the locksmith about restrictions. A professional will ask questions about the key's purpose; this is a good sign.
- Get a quote in writing. Prices vary widely for restricted keys ($10–$100+), so compare.
- Bring proof of ownership if needed. A property deed, purchase receipt, or rental agreement can expedite the process.
When comparing key-cutting services, Mercoly helps you find trusted providers in your area who understand these legal nuances and can advise on whether your duplication request is feasible.
Frequently Asked Questions
Q: Can a locksmith refuse to cut my key? Yes, and they're legally protected if they do. If the key is marked "DND," appears patented, or the locksmith suspects misuse, they can decline—and reputable ones will.
Q: What happens if I try to duplicate a government key? Duplicating keys to federal property without authorization is a federal crime that can result in fines and imprisonment; state laws vary for other restricted keys.
Q: How long does it take to duplicate a restricted key? Standard keys take 5–10 minutes at any hardware store; high-security or patented keys through a specialist locksmith typically take 1–3 business days if the blank must be ordered.
Find a trusted key-cutting provider near you who can verify your duplication request and handle restrictions properly.