Subclass Characteristics (Footwear)
Definition
Features shared by a subset of shoes from the same mould or production batch; may mimic individual characteristics if not properly distinguished.
- Level
- Between class and individual characteristics
- Origin
- Same mould or production batch of a shoe
- Evidence type
- Footprints, tyre marks and casting
- Risk
- May mimic individual characteristics if not distinguished
Common questions
How can a shoe mould leave a batch-shared feature?+
A mould can carry a manufacturing flaw, such as a small defect or wear spot, from the moment it is made or as it degrades over production. Every shoe sole cast from that mould before it is replaced or repaired will carry the same feature, independent of how any individual shoe is later worn.
Why does this matter more for footwear than for many other impression evidence types?+
Popular shoe models are mass produced in large numbers from a limited set of moulds, so the pool of shoes sharing a mould-level feature can be large. An examiner must account for how common a given sole pattern and mould defect are before treating wear-based features as individualising.
Related terms
- Class Characteristics (Footwear)
- The manufactured outsole design features shared by all examples of a specific shoe model: tread pattern, size, shape, and logo placement.
- Dental Stone
- A gypsum-based casting material harder and finer than plaster of Paris. Preferred for forensic 3-D casts because it captures detail at the...
- ESLA (Electrostatic Dust-Print Lifter)
- A device that applies a high-voltage static field to a metallised film, attracting dust particles from a footwear impression on a hard...
- Perpendicular Camera Alignment
- The requirement that the camera lens be directly above the impression centre with the sensor plane parallel to the impression plane; prevents...
- R V. Mohan (1994) + White Burgess Langille Inman (2015)
- Canadian Supreme Court framework for forensic-expert admissibility: Mohan sets relevance + necessity + qualification + no exclusionary rule; White Burgess adds an...
- Randomly Acquired Characteristics (RACs)
- Post-manufacture features (cuts, gouges, embedded material, crack patterns) unique to a specific shoe sole or tyre; the highest-level individualising features in impression...
- SICAR (Shoeprint Image Capture and Retrieval)
- FBI and Foster and Freeman (UK) outsole design database used for class-characteristic database searches; referenced in US, UK, Australian, and Canadian forensic...
- Snow-Print Wax
- A spray wax applied in thin coats to snow impressions before casting to provide a thermal barrier, allowing Dental Stone casting without...
- SWGTREAD
- Scientific Working Group for Shoeprint and Tire Tread Evidence; US body that developed the dominant guidelines for footwear and tyre-mark examination, class-subclass-individual...
- Tracking Evidence (TE) Database
- FBI database of tyre tread design patterns, used for class-characteristic identification in tyre-mark cases; accessible to partner agencies internationally.
- Treadmate
- RCMP database of outsole designs for footwear comparison, used by Canadian forensic laboratories and accessible to partner agencies.