Negative Corpus
Definition
The discredited practice of concluding incendiary fire cause by eliminating all identifiable accidental causes without positive physical evidence of intentional fire-setting. NFPA 921 (since 2011) and US courts applying Daubert identify this as inconsistent with the scientific method.
- Official rejection date
- NFPA 921 rejected negative corpus in 2011
- Legal standard
- Rejected by US courts under Daubert and equivalent bodies in UK and Australia
- Scientific basis
- Inconsistent with the scientific method
Common questions
What is the negative corpus approach in fire investigation?+
Negative corpus is an investigative method where an investigator concludes a fire was deliberately set (arson) by eliminating all accidental and natural causes, but without finding positive physical evidence that someone intentionally started it. It relies purely on ruling things out, not proving arson happened.
Why is negative corpus now rejected by fire investigators?+
NFPA 921 has rejected negative corpus since 2011 because it is inconsistent with the scientific method. US courts applying Daubert standards, as well as courts in the UK and Australia, have identified this approach as unreliable for determining incendiary cause. The method was central to criticisms in wrongful conviction cases like the Willingham case.
What should investigators do instead of using negative corpus?+
Investigators should look for positive physical evidence of intentional fire-setting, rather than simply eliminating accidental causes. This evidence-based approach aligns with scientific methodology and meets the legal standards required in modern court systems.
Related terms
- NFPA 921
- US National Fire Protection Association Guide for Fire and Explosion Investigations. The internationally accepted methodology Indian fire investigators and SFSL fire divisions...
- ASTM E1618
- Standard Test Method for Ignitable Liquid Residues in Extracts from Fire Debris Samples by Gas Chromatography-Mass Spectrometry. The active analytical standard defining...
- Flashover
- The near-simultaneous ignition of all exposed combustible surfaces in a compartment, occurring when the upper gas layer reaches approximately 600°C and radiative...
- 360-Degree Imaging
- Panoramic imaging systems (Matterport, Leica RTC360, FARO Focus) producing navigable point clouds and photospheres of fire scenes, enabling retrospective measurement and remote...
- ABE Guidance
- Achieving Best Evidence in Criminal Proceedings, the UK guidance framework published by the Ministry of Justice governing how investigators should conduct interviews...
- ACM-PE Cladding
- Aluminium composite material with a polyethylene core (Reynobond PE). The combustible cladding type responsible for external fire spread at Grenfell Tower. Now...
- Annealing
- The heat-induced reorganisation of the crystal structure of steel at temperatures above approximately 720°C, resulting in reduced hardness and tensile strength; measurable...
- Arc Bead
- A small, rounded, resolidified deposit of copper or aluminium formed when an electrical arc melts the conductor and the material rapidly re-solidifies;...
- Arc-Flash Bead Metallurgy
- Forensic metallurgical analysis of conductor wire segments to distinguish between arc-flash ignition (producing globular fusion beads) and mechanical fracture followed by fire...
- ASTM E1188
- Standard Practice for Collection and Preservation of Information and Physical Items by a Technical Investigator, the companion evidence-preservation standard to NFPA 921...
- Backdraft
- A deflagration event triggered when air is suddenly admitted to a compartment where a fire has been oxygen-depleted but has continued to...
- BS 8414-1
- British Standard for external wall systems: fire performance test for facade assemblies. The large-scale test that ACM-PE cladding, as installed at Grenfell...
Explained in these topics
- Fire Chemistry, Pyrolysis and the Arson Investigation FrameworkThe discredited investigative approach of determining arson by eliminating accidental and natural causes without positive evidence of human intentional act. Re...
- Fire Scene Examination and the NFPA 921 Systematic MethodologyThe discredited practice of concluding incendiary fire cause by eliminating all identifiable accidental causes without positive physical evidence of intentiona...
- Major Arson Casework: Station Nightclub, Grenfell, Uphaar, Kamala MillsA prohibited methodology under NFPA 921 whereby an investigator declares arson by eliminating all accidental causes without positive physical evidence of incen...
- Origin and Cause: V-Patterns, Char Depth, Electrical IndicatorsA discredited approach to incendiary cause determination that concludes arson by eliminating all identifiable accidental causes, without positive physical evid...