When and why did the Board for Certification of Genealogists(R) stop using the term "preponderance of the evidence" to describe how genealogists evaluate evidence.

Today, genealogists who work to follow BCG's standards apply the Genealogical Proof Standard (GPS)?

What practical impact did the change in POE have on the approaches taken by genealogists who work to apply BCG's standards and more specifically, practice the GPS?

From an article on the BCG website, in part:

BCG Abandons the Term "Preponderance of Evidence"

The Board for Certification of Genealogists, which tests and certifies researchers in a number of genealogical specialties, will no longer use the term preponderance of evidence, heretofore widely used to describe how genealogists analyze and weigh evidence ...


2 Answers 2


I think the change is a positive one that clarifies the evaluation of evidence. As someone who finds they like things spelled out clearly, the five criteria listed below (taken from the website you cite) are more specific that the vague legal term "Preponderance of Evidence" which can be defined as "A requirement that more then 50% of the evidence points to something"

Five criteria which apply to the Genealogical Proof Standard (GPS)

  • a reasonably exhaustive search;
  • complete and accurate source citations
  • analysis and correlation of the collected information
  • resolution of any conflicting evidence
  • a soundly reasoned, coherently written conclusion

Also, kudos on introducing this topic to this SE site as appropriate for both questions and answers given!

  • 3
    Agreed - I'd not be comfortable with the idea that two records saying one thing automatically over-ride one saying another without any evaluation over whether those 2 are independent, reasonable, etc., or whether there are other obvious sources of evidence omitted. Was the change to the 5 point GPS actually material, do you know, or was it a case of doing all those things while still using this vague term as an incorrect summary?
    – AdrianB38
    Commented Oct 31, 2012 at 17:50
  • @AdrianB38 In terms of materiality and while I hope others will answer, establishing the GPS moved genealogy/family history into a unique discipline. I think we still borrow greatly from law in terms of describing evidence, but the application or proof is distinct/unique (different from law).
    – GeneJ
    Commented Oct 31, 2012 at 22:47
  • Gene - I don't see any uniqueness as an issue. I'm still not sure if the GPS is a process or a set of measures to be applied at the end of a process (or both!) but any discipline has its own processes and measures, so nothing unusual in Genealogy/FH having its own. After all, the burden of proof is different btw civil and criminal (or it is in the UK) and I've no ideas about what's required in employment tribunals. I'm sure I read that the GPS was intended to aim btw PoE and "beyond a reasonable doubt" as for criminal courts. So not that far out?
    – AdrianB38
    Commented Nov 1, 2012 at 11:27
  • Just looked at Helen Leary's article. The impression I get on a swift read (domestics await..) is of it being a change in name, a refinement of words, a clarification, an avoidance of buzz-words found on TV, rather than a material change in what was actually done. So I warm to the view that this is another case (as with primary source v. primary evidence) of FH simply being more explicit in its requirements rather than different in essence. Doesn't mean there aren't genuine differences created...
    – AdrianB38
    Commented Nov 1, 2012 at 11:52

The change in terminology indicates new preferences, a different attitude, and a changed mindset. Whether it has altered practice is another matter entirely.

Equating the term "preponderance of evidence" with a pass mark of 50% carries with it the assumption that evidence comes in uniform packets that can be counted. In fact the prevailing metaphor in the law is that evidence is "weighed"; a view that reflects that two claims may have very different worth.

The feature of the burden of proof adopted in civil (but not criminal) law from which genealogists may wish to distance themselves is "on the balance of probability" sometimes represented as "more likely than not".

The claim of the Genealogical Proof Standard (GPS) is that its consistent application will produce a greater level of confidence in conclusions than "probably". Note however that it would be unrealistic for genealogists to aspire to a scientific standard of p-values or confidence intervals. That would be inconsistent with other aspects of the ways in which they work.

It is interesting that the products of forensic genealogy undertaken to justify a claim on a deceased estate will be assessed by a court against the very standard of proof that the BCG wishes to eschew -- on the preponderance of the evidence.

  • Nice comment about forensic genealogists and the resulting assessment being on PoE. I do wonder though if we are misleading ourselves about being so different from civil law. I retain some faith that a prosecution lawyer who only conducted a search for evidence in a few, easy areas, would get their case rejected even though the PoE of what was found was in their favour. Or that the defence lawyer would have completed in the "reasonably exhaustive search". Even if the phrase isn't used by them?
    – AdrianB38
    Commented Nov 1, 2012 at 11:37
  • Perhaps a forensic genealogist will comment or, better yet, add a separate question and/or answer. Regional differences/notions aside, in my experience, experts are first qualified by the court in order for their testimony/evidence to be considered. Notions of POE then are considered by juries.
    – GeneJ
    Commented Nov 1, 2012 at 12:48

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