Distinguishing physical characteristics are permanent or semi-permanent body features — scars, tattoos, birthmarks, limb differences, medical implants — that are rare and stable enough to pick one person out of a crowd of others who share the same general height, build, age, and coloring. Government agencies record them on passports, driver’s licenses, and law enforcement databases because common descriptors match too many people to narrow an identification. A surgical scar in a specific location or a tattoo with recognizable imagery can resolve an identity question that height and weight cannot.
What Makes a Feature Count
Two tests decide whether a feature is a distinguishing characteristic rather than a general descriptor: rarity and permanence. The practical question is whether an observer could use the feature to pick you out of a group of people who otherwise look similar. A trait shared by a large slice of the population adds almost nothing to an identification profile.
Permanence matters nearly as much. Hair length, facial hair, and body weight get recorded on IDs, but they describe you today rather than you in six months, so agencies treat them as general descriptors. The features that carry real identification weight are the ones that stay consistent over years or decades.
The Main Types
Scars and Surgical Marks
Scars are among the most reliable identifiers because every scar has a unique shape, texture, and location. A keloid scar on the left forearm from a childhood accident reads differently from a similar scar on someone else’s right hand. Surgical scars carry extra value because their placement often lines up with a specific procedure, giving a second data point to cross-reference against medical records.
Tattoos
Tattoos are documented in unusual detail. Imagery, ink colors, size, and exact body location all become searchable data. A sleeve of koi fish on the left arm is a fundamentally different identifier than a small anchor on the right wrist, even though both are “tattoos.” Law enforcement databases track removed tattoos separately, since the faint outline or skin texture change left behind is itself a distinguishing mark.
Birthmarks, Moles, and Skin Conditions
Large birthmarks and prominently placed moles work as natural identifiers that require no action on your part. A port-wine stain across the left cheek or a cluster of raised moles on the neck stays essentially unchanged from childhood. Vitiligo, prominent freckle patterns, and other visible skin conditions can also qualify when they appear in uncommon configurations.
Limb Differences and Prosthetics
Missing fingers, limb differences, or the permanent use of a prosthetic are powerful identifiers because they affect a small fraction of the population and are nearly impossible to disguise. Agencies record the specific nature of the difference, not just its existence. “Missing right index finger” is a more useful data point than “hand abnormality.”
Medical Implants
Orthopedic implants and other surgically placed devices have become increasingly important in forensic identification, especially when fingerprints or dental records are not available. Each implanted device carries a serial number that can be traced through the manufacturer back to the hospital, surgeon, and patient. In a study of forensic cases where standard identification methods failed, more than half of cases involving implanted devices were resolved by matching serial numbers to medical records.1National Center for Biotechnology Information. The Use of Orthopedic Surgical Implants for Forensic Identification: An Overview The method has worked even in mass disasters, where remains may be too damaged for visual or DNA-based approaches.
Describing a Mark on a Government Form
When a form asks for “distinguishing marks” or “scars, marks, and tattoos,” aim for a description specific enough that someone reading it could recognize the feature on sight. “Scar on arm” is nearly useless. A good entry has three parts: the type of feature (scar, tattoo, birthmark), its precise location (left forearm, two inches above the wrist), and a physical description (linear, approximately four centimeters, darker than surrounding skin).
The U.S. passport application (Form DS-11) includes fields for these details, which passport agencies use to build an identification profile that supplements the photograph.2U.S. Department of State. Application for a U.S. Passport DS-11 Driver’s license applications in most states collect similar data, though detail varies. Some states ask only for height and eye color; others have dedicated fields for scars and tattoos.
If you have several marks, prioritize the most visible and permanent. A large facial scar or a full-sleeve tattoo carries more weight than a small mole typically covered by clothing. For tattoos, note the primary imagery rather than attempting an exhaustive description. “Dragon tattoo, right upper arm, full color” communicates more than a paragraph an examiner would struggle to parse.
How Law Enforcement Uses the Data
The NCIC Database
The National Crime Information Center is the primary federal system for sharing identification data across law enforcement agencies. Its purpose is to provide a computerized database any authorized criminal justice agency can query for prompt information about crimes and individuals.3Federal Bureau of Investigation. National Crime Information Center When officers enter someone into NCIC, scars, marks, and tattoos get their own coded fields using a standardized abbreviation system. Scars are logged with an “SC” prefix followed by a body location code, tattoos with “TAT,” needle marks with “NM,” and removed tattoos with “RTAT.”4National Institute of Standards and Technology. NCIC Scar Codes Table Investigators can then search for specific feature combinations across millions of records.
The practical effect is dramatic. A search for a white male in his thirties returns thousands of potential matches. Add “tattoo, left neck, spider web” and the pool shrinks to a handful.
Missing and Unidentified Persons
Distinguishing characteristics are often the key to resolving cases involving unidentified remains or long-term missing persons. NCIC missing-person entries include mandatory fields for height, weight, eye color, and hair color, plus optional fields for scars, marks, tattoos, blood type, and medical implant information. When remains are recovered, investigators compare visible or radiographic features against those entries. The Department of Justice also runs the National Missing and Unidentified Persons System (NamUs), which cross-references detailed physical characteristic data between missing-person reports and unidentified remains. When fingerprints and dental records are not available, a documented tattoo or surgical scar may be the only path to identification.
Updating Records After a Change
Documented characteristics don’t have to stay frozen. People remove tattoos, undergo reconstructive surgery, or acquire new scars. When those changes affect identification, records should catch up.
For passports, the State Department draws a clear line. Growing a beard, coloring your hair, or aging normally does not require a new passport. Significant facial surgery, adding or removing large facial piercings or tattoos, and major weight changes do qualify as significant appearance changes requiring a new application.5U.S. Department of State. U.S. Passport Photos The test: if you can still be identified from your current photo, you’re fine. If not, apply for a new one.
Driver’s license updates typically require visiting your state’s motor vehicle office and paying a correction or replacement fee, generally $11 to $40 depending on the state. Some states allow minor corrections online; others require an in-person visit with updated documentation. If you’ve had a listed tattoo removed or acquired a significant new scar, updating the record keeps your ID accurate for law enforcement encounters and identity verification at airports.
Your Rights Over the Data
Physical characteristic data in federal systems carries legal protections. The Privacy Act of 1974 governs how federal agencies collect, maintain, and share records about individuals. No agency may disclose a record from a system of records without your written consent, unless the disclosure falls under one of thirteen specific exceptions covering law enforcement needs, congressional inquiries, court orders, and statistical research where your identity is stripped from the data.6Office of the Law Revision Counsel. United States Code Title 5 – 552a The Act also gives you the right to access your own records and request corrections.
Access to NCIC data is restricted by federal regulation. Criminal history record information may be shared with criminal justice agencies for law enforcement purposes, federal agencies authorized by statute, entities conducting background checks under federal law, and a limited set of private contractors operating under security agreements approved by the Attorney General.7eCFR. 28 CFR 20.33 – Dissemination of Criminal History Record Information Agencies that contribute data to these systems must keep it complete, accurate, and current, and an agency that fails to comply risks losing its connection entirely.8eCFR. 28 CFR Part 20 – Criminal Justice Information Systems
If you believe your physical description in a federal database is wrong, you have the right to review it and request amendments. For FBI-maintained records, the process is set out in 28 CFR §§ 16.30 through 16.34. For state or local agencies that feed into the federal system, your state’s own correction procedures apply, and federal rules require those agencies to maintain accuracy as a condition of continued access.