Misuse of Tanner Scale
PEDIATRICS Vol. 102 No. 6  December 1998, pp. 1494
Misuse of Tanner Puberty Stages to Estimate Chronological Age

To the Editor;
One of us has been involved as an expert in several US federal cases of possession of alleged child pornography, in which seized materials (videos, photographs, computer downloads) were used as evidence against individuals identified in "sting" operations, wherein government agents take over pornographic businesses.  In these cases the staging of sexual maturation (Tanner stage) has been used not to stage maturation, but to estimate probable chronological age.  This is a wholly illegitimate use of Tanner staging: no equations exist estimating age from stage, and even if they did, the degree of unreliability in the staging the independent variable would introduce large errors into the estimation of age, the dependent variable.  Furthermore, the unreliability of the stage rating is increased to an unknown degree by improperly performed staging, that is, not at a clinical examination but through nonstadardized and, thus, unsuitable photographs.
Therefore, we wish to caution pediatricians and other physicians to refrain from providing "expert" testimony as to chronological age based on Tanner staging, which was designed for estimating development or physiologic age for medical, educational, and sports purposes, in other words, identifying early and late maturers.  The method is appropriate for this, provided chronologic age is known.  It is not designed for estimating chronologic age and, therefore, not properly used for this purpose.

Arlan L. Rosenbloom, MD
Department of Pediatrics
University of Florida College of Medicine
Gainsville, FL 32610-0296

James Tanner, MD, PhD
University of London
London, England

Pediatrics (ISSN 0031 4005).Copyright© 1998 by the American Academy of Pediatrics Reprint (PDF) Version of this Article

Detective McLaughlin wrote this letter in response to the above letter;

December 16, 1998

Dr. Arlan Rosenbloom
University of Florida College of Medicine
Department of Pediatrics
Gainsville, Florida 32610-0296

Dear Dr. Rosenbloom,

I saw your letter in Pediatrics (Dec./98) about the use of the Tanner Scale. I am a police detective that works on cases of child pornography on the Internet. If I understand your letter, you state that the Tanner Scale should not be referenced when a pediatrician testifies regarding the age of a subject in a photograph(s). I assume this does not interfere with a pediatrician forming an opinion regarding the age of the subject in a photograph, relying on their experience of examining children. The New Hampshire Rules of Evidence allow for an expert to give an opinion based on his “knowledge, skill, experience, training, or education….” If I understand your letter, this ability to do so would not be interfered with. You want this expert not to form an opinion based using the Tanner Scale, but on other factors such as their clinical experience.

All of this might not even be necessary given that a lay person can testify about such things as speed, height and age without being qualified as an expert. A lay witness can testify to his opinion based on inferences which are rationally based on perceptions, such as the age of an individual. Expert testimony is generally only needed, and/or permissible when scientific, technical, or when other specialized knowledge will assist the jury, or Judge in some instances,  to understand evidence or make a fact determination. Many investigators  show child pornographic images to pediatricians when developing probable cause, a procedure I have always questioned and felt unnecessary. It seems to me that a panel of jurors might also be able to make an age determination without expert testimony.

James F. McLaughlin

Detective McLaughlin received this reply from Dr. Rosenbloom;

January 21, 1999

James F. McLaughlin
Keene Police Department
11 Washington St.
Keene, NH 03431

Dear Detective McLaughlin;

Thank you for your very thoughtful letter regarding our communication in Pediatrics regarding the misuse of the Tanner scale.  This letter has generated a number of calls from pediatricians who provide expert testimony about child pornography and consider the Tanner staging to be important in their judgment.  My response is essentially what you have so lucidly stated, that one does not need the Tanner staging to determine whether one is dealing with a child or a sexually mature individual, and given sexual maturity, that it is extremely difficult to assign chronologic age from the available material.  There is a great variability in the timing of various stages, and pubic hair, which forms an important part of Tanner staging, is unreliable for staging Asians and is frequently trimmed or shaved completely in pornography.  Pornographers may also prefer to use individuals who appear quite young for their greater prurient interest.

The kinds of judgments that can be made, as you note, can generally be made by lay persons.  An experienced pediatrician, however, will have a professional perspective on the range of normality in terms of development for age.  The physicians I have talked to are, in fact, circumspect in their use of the Tanner stage, to the point that they really don't need the Tanner stage!  Tanner staging is useful for notations in medical records and standardizing observations among physicians and for clinical research.  The kinds of judgments that need to be made, however, were made before we had Tanner stages, with no less expertise or accuracy.

Once again, thank you for sharing your perspective.  We may need to write a clarifying letter, and your input will be helpful in that effort.


Arlan L. Rosenbloom, MD
Distinguished Service Professor Emeritus

C: James F. Tanner, MD, PhD

Reprinted by permission of Detective James F. McLaughlin, October 4, 1999.

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