Verbal Scale
Definition
The ENFSI translation of numerical likelihood ratios into courtroom language: very strong support (LR over 10,000), strong support (LR 1,000-10,000), moderate support (LR 100-1,000), limited support (LR 10-100). Used by UK, Dutch, Swedish, and Australian forensic laboratories as the standard testimony format for pattern evidence opinions.
- Standard framework
- ENFSI translation of numerical likelihood ratios into courtroom language with four support levels (very strong, strong, moderate, limited)
- Common use
- Pattern evidence testimony including fingerprints and DNA comparisons
- Jurisdictions
- UK, Netherlands, Sweden, Australia
Common questions
What is a verbal scale in forensic testimony?+
A verbal scale translates numerical likelihood ratios into plain courtroom language so judges and juries can understand the strength of evidence. Instead of citing a raw number, an expert says something like 'strong support'. This makes statistical evidence accessible without requiring listeners to grasp probability math.
What are the main verbal scale categories?+
The ENFSI standard has four levels: very strong support (LR over 10,000), strong support (LR 1,000-10,000), moderate support (LR 100-1,000), and limited support (LR 10-100). These phrases appear in testimony when experts express their conclusions about pattern evidence like fingerprints or DNA comparisons.
Which countries use verbal scales as standard?+
The UK, Netherlands, Sweden, and Australia all use ENFSI verbal scales as their standard format for pattern evidence opinions in court. The standardized phrases help ensure consistency across jurisdictions and make expert testimony more understandable to non-specialists.
Related terms
- Likelihood Ratio (LR)
- The ratio of two conditional probabilities: the probability of the observed evidence given the prosecution's hypothesis (same source), divided by the probability...
- ENFSI Guideline for Evaluative Reporting
- A consensus guidance document from the European Network of Forensic Science Institutes that defines how member laboratories should express evaluative opinions. It...
- 2009 NAS Report
- The National Academy of Sciences report Strengthening Forensic Science in the United States, which found that fingerprint individualization claims lacked empirical population-frequency...
- Accreditation Body
- A national or regional organisation that assesses laboratories against ISO/IEC 17025 and grants accreditation. Examples include UKAS (United Kingdom Accreditation Service), NIST-associated...
- Categorical Identification
- The historical fingerprint testimony model in which the examiner declares that the latent print originated from the named person to the exclusion...
- Daubert Standard
- The US federal evidentiary standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) requiring that expert testimony be based on scientifically valid methods with...
- Duty of Impartiality
- The obligation that an expert witness owes to the court rather than to the party that retained them. Codified in England and...
- ENFSI Evaluative Reporting Framework
- The ENFSI Guideline for Evaluative Reporting in Forensic Science (2015), which specifies that forensic identification opinions should be expressed as likelihood ratios...
- Evaluative Conclusion
- A forensic opinion that addresses the weight of the evidence, typically expressed as an LR or a verbal equivalent. Distinct from a...
- Factual Section vs Interpretation Section
- A structural distinction in expert reports between what was observed (verifiable facts, not requiring expert judgment) and what those observations mean (expert...
- FRStat
- The fingerprint statistical scoring model developed by the FBI Laboratory and Iowa State University (Professor Alicia Carriquiry). Takes ACE-V comparison documentation as...
- Frye Standard
- The US legal test for admissibility of scientific evidence, originating from Frye v. United States (1923), which required that a technique be...
Explained in these topics
- Evaluative Opinion Standards and FrameworksA standardised mapping from likelihood ratio values to descriptive phrases used in court-facing reports. The ENFSI scale runs from 'weak support' through 'mode...
- Expert Reporting and Court Testimony in Forensic BotanyA standardised set of phrases (such as 'strongly supports', 'provides moderate support', 'is consistent with') used to express likelihood ratios in non-numeric...
- FRStat, Likelihood Ratios and the Post-2009 NAS DebateThe ENFSI translation of numerical likelihood ratios into courtroom language: very strong support (LR over 10,000), strong support (LR 1,000-10,000), moderate...
- Verbal Equivalents of the Likelihood RatioA published table that assigns a plain-language phrase to each numerical range of LR values, allowing evaluative conclusions to be communicated in court withou...