Report Writing and Evidential Standards

The cleanest forensic reports share a common architecture, because that architecture reflects how courts evaluate evidence. Courts accept measurements, photographs, and catalogue entries as factual record. They scrutinise interpretation. If interpretation is embedded in the factual description, the reader cannot tell where observation ends and opinion begins. Experienced opposing counsel will find every point where this happens and use it to suggest that the whole report is contaminated by the expert's opinion rather than grounded in observation.

• Summary of conclusions: placed first for judges and juries who need to grasp the main points quickly. Should not appear without the detailed sections that support it.
• Qualifications and instructions: the expert's relevant experience and the scope of what they were asked to assess. This frames what falls within and outside their expertise.
• Materials examined: a complete inventory of everything reviewed, from context sheets and photographs to laboratory reports and artefact catalogue. If something was not examined, the report must say so.
• Factual findings: observations, measurements, photographs, and analytical results. No conclusions, no 'suggesting that', no 'consistent with.' Pure data.
• Interpretation: what the facts mean, expressed in probabilistic language with stated confidence levels and acknowledged alternative explanations.
• Declaration and signature: in most jurisdictions a formal statement that the report is complete, accurate, and that the expert's duty is to the court rather than to the instructing party.

The threshold for admissible expert evidence varies by jurisdiction. An expert who does not understand the standard applicable in the court they are addressing is not prepared to give reliable evidence. The two principal US standards are Daubert and Frye; UK law has its own test; international tribunals have their own rules. Each addresses the same underlying problem: courts are not equipped to evaluate scientific validity directly, so they need a gatekeeping mechanism to prevent unreliable methods from prejudicing proceedings.

For established forensic archaeology methods, admissibility challenges typically focus not on the method category but on how it was applied in the specific case. A challenge to single-context recording is unlikely to succeed because the method has decades of peer-reviewed application and archaeological consensus. A challenge to a particular GPR interpretation in a specific site with difficult soil conditions is more plausible, because it questions the analyst's application of the method to this soil type, not the method in principle. Anticipating this distinction helps the expert prepare.

Criminal proceedings in adversarial common-law jurisdictions require the strictest report form. The expert must address the possibility that their opinion will be challenged by a well-prepared opposing expert, and must not present conclusions that go beyond what the evidence can bear. The burden of proof is criminal standard (beyond reasonable doubt in most systems), and the expert's role is to inform the fact-finder, not to provide the answer.

Coronial proceedings in England and Wales aim to establish who died, how, when, and where. The standard of proof is the balance of probabilities for most findings. The coroner is inquisitorial rather than adversarial; the expert faces fewer hostile opposing-expert challenges and is instead examined by the coroner or interested parties. Reports for coronial inquiries can be somewhat less formal in structure than criminal reports, but must still clearly distinguish factual findings from interpretation and must not express legal conclusions (such as unlawful killing) which are the coroner's determination, not the expert's.

International tribunal reporting for the ICTY, ICC, or ad hoc mechanisms has its own requirements. Reports are typically translated into multiple languages; the expert must avoid idiomatic expressions that translate poorly. Reports often address large-scale events (mass graves, systematic killings) where the expert's conclusions on burial typology, execution evidence, and body movement feed into criminal charges such as genocide or crimes against humanity. The UN Manual on the Effective Prevention and Investigation of Extra-Legal, Arbitrary and Summary Executions provides guidance on minimum investigative standards, and reports departing from those standards may be challenged on methodology.

Expert witnesses sometimes hedge conclusions so heavily that the report provides no usable guidance, or overclaim certainty in an attempt to appear decisive. Both failures carry professional risk. Courts can identify both patterns. The solution is to express uncertainty in a way that is specific enough to be meaningful and honest about what the evidence cannot resolve.

• Quantify where possible: a radiocarbon result should state the 95% confidence range. An OSL date should state its standard deviation. A probability-based conclusion (the burial is more likely than not to be post-1950) should identify what evidence drives that probability.
• Use graduated language consistently: 'establishes' means the evidence leaves no reasonable alternative; 'strongly supports' means the evidence favours one interpretation significantly; 'is consistent with' means the evidence does not exclude an interpretation; 'does not support' means the evidence actively points against. Using these terms interchangeably erodes credibility.
• Address alternative hypotheses: for every major conclusion, state the alternative that the evidence most seriously competes with, and explain why the stated conclusion is preferred. A report that considers and rejects alternatives is more robust than one that states conclusions without acknowledging that alternatives exist.
• Identify what further analysis could resolve: if a question cannot be resolved from the current evidence but could be addressed by additional analysis, say so. Courts can direct that work, and failing to flag what is possible may leave a critical question unanswered unnecessarily.

The site archive, including all context sheets, field notebooks, photographic records, sample registers, and digital survey data, is not supplementary to the report. It is the primary evidence. The report is a structured interpretation of the archive. In legal proceedings, both may be subject to disclosure, and the archive may be examined by opposing experts to test whether the report accurately reflects what was observed.

This means field documentation must be completed to a standard suitable for legal examination from the first moment of a forensic recovery. An archaeologist who notes something informally in a field notebook but omits it from the context sheet creates a discrepancy that opposing counsel can use. Photographic metadata (date, time, GPS if available) must be preserved intact. Digital survey data must be stored in a format that remains accessible without proprietary software. Chain-of-custody documentation for physical samples must be complete and unbroken.

In England and Wales, the expert's overriding duty is to the court, codified in Criminal Procedure Rules 2020 Part 19 and Civil Procedure Rules Part 35. In the US federal system, the same principle is embedded in FRE 702 and the broader ethical rules governing expert testimony. Internationally, tribunal rules impose equivalent standards. The implications are concrete: the expert must disclose all material observations, including those inconsistent with the instructing party's case, and may not express a conclusion they do not genuinely hold just because the instructing party wants a stronger statement.

Disclosure obligations have become more pressing as digital evidence has grown. Field photographs stored on personal devices, GPS tracks from handheld instruments, email communications about interpretive uncertainty, and draft reports circulated before finalisation may all be discoverable in litigation. An expert who expresses genuine doubt in an email to the instructing solicitor and then presents unqualified certainty in the final report has created a serious inconsistency. The standard practice is to communicate analytical conclusions consistently across all channels from the outset.

• Peer review and disclosure: many instructing parties routinely circulate draft forensic archaeology reports to a peer reviewer before finalisation. This is good practice. The peer review comments and the expert's responses to them may be disclosable, which means the review process must be conducted as if the comments will be seen by opposing counsel.
• Instruction to limit scope: an instructing party may ask an expert to address only specific questions and not to examine certain aspects of the evidence. The expert must assess whether complying with this instruction would result in a misleading report. If it would, they must either expand their scope or decline the instruction.