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# Treating doctor and expert witness: two roles that do not mix

- Topic

The treating doctor cares for the patient; the expert reports impartially to the court. Playing both roles with the same person creates conflicts.

Updated Nov 13, 2026

## Key points

- Treating doctor = beneficence and secrecy; expert = impartiality before the court.
- Always tell the person examined who requested the examination and who receives the report.
- The judge's disqualification grounds apply to experts (Law 906, art. 411).
- Avoid being the expert for one's own patient; if there is no alternative, transparency and separate records.
- The doctor-patient relationship exempts from the duty to testify as a witness (Law 906, art. 385).

## What it is

The treating doctor owes the patient beneficence and loyalty, and keeps the patient's secret. The expert serves justice: examines impartially, reports findings to the judge or prosecutor and testifies at trial, whether or not this favours the person examined. The two roles clash: a person may tell the expert what they would tell their own doctor, believing it protects them, and a treating doctor acting as expert may lean towards the patient or use against them what was learned in confidence. Law 23 of 1981 recognises the doctor as an aid to justice, as a public official or as an appointed expert (art. 1, item 6), and the World Medical Association asks that when doctors act for a third party, they tell the patient so from the outset. In criminal proceedings, the judge's grounds for disqualification apply to experts (Law 906 of 2004, art. 411), such as having given advice or an opinion on the matter, or close friendship or serious enmity with a party (art. 56, items 4 and 5), and the doctor-patient relationship is an exception to the duty to testify (art. 385). How an expert examination is done is explained in Forensic medicine; this page deals with the ethical conflict.

## Key facts

- Treating role: beneficence, confidentiality and advocacy for the patient's health interests.
- Expert role: impartiality and truthfulness before the authority; the report goes to whoever requested it, not only to the person examined.
- Law 23 of 1981, art. 1, item 6: the doctor is an aid to justice as a public official or as an expressly appointed expert.
- Law 906 of 2004, art. 411: the judge's grounds for disqualification and challenge apply to experts; they include having given advice or an opinion on the matter and close friendship or serious enmity with a party (art. 56, items 4 and 5).
- Law 906, art. 385(b): the doctor-patient relationship is an exception to the duty to testify as a witness.
- World Medical Association, International Code (2022), para. 23: when acting on behalf of a third party, the doctor tells the patient at the outset; para. 8: certify only what one has personally verified.

## Step by step

- Before examining, tell the person who the doctor is, who requested the examination and who will receive the report.
- Explain that the expert examination is not a consultation and that what they say may appear in the report.
- Ask for consent to the examination and respect a refusal, recording it.
- If the doctor is or was this person's treating doctor, tell the authority and consider whether a disqualification applies.
- Keep separate records: the treatment medical record and the expert report.
- Report only what was observed and what is inferred on sound grounds, within one's own field.

## In clinical practice

- The emergency doctor treats and documents the injuries of an assault victim and gives the notice the law requires; that doctor does not become the expert who sets the medico-legal incapacity.
- A treating psychiatrist should not assess the criminal responsibility of their own patient: they know a lot but are not impartial, and they would endanger the therapeutic relationship.
- In a rural post with no other doctor, the same professional may have to act as treating doctor and expert: they say so clearly to the person and keep both records separate.
- An insurer asks a doctor to examine a claimant: the person examined must know the doctor works for the insurer.

## Legal framework in Colombia

- Law 23 of 1981, art. 1, item 6: the doctor as an aid to justice.
- Law 906 of 2004, arts. 56, 385 and 411: grounds for disqualification that apply to experts, and the exception to the duty to testify for the doctor-patient relationship.
- Expert examination, the expert report and testimony at trial are covered in Forensic medicine; the duty to notify when receiving an injured person (Law 906, art. 218), under the duty to report crimes.
- Official texts verified on 2026-11-13 on funcionpublica.gov.co.

## Test yourself

Think of the answer, then tap the question to see it.

## What must a person know before an expert examination?

Who the doctor is, who requested the examination, that it is not a consultation and that the report will go to the requesting authority; with that information they decide whether to consent.

## Which grounds for disqualification apply to experts in Colombian criminal proceedings?

The same as for the judge (Law 906 of 2004, art. 411), for example having given advice or an opinion on the matter, or close friendship or serious enmity with a party (art. 56).

## Why should a doctor not act as expert for their own patient?

Because impartiality is lost and what was learned in confidence may be used or disclosed; it also damages the therapeutic relationship.

## What does the World Medical Association ask when a doctor acts for a third party?

That the doctor tell the patient at the outset and, where appropriate, during the interaction (International Code of Medical Ethics, 2022, para. 23).

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## Elsewhere in DurgiPedia

- [The doctor as expert witness (perito) under Law 906 of 2004](https://durgical.com/en/forensic-medicine/the-doctor-as-expert-witness-under-law-906-of-2004/)
- [Testifying as an expert at the oral trial](https://durgical.com/en/forensic-medicine/testifying-as-an-expert-at-the-oral-trial/)
- [The duty to report a crime and its limits](https://durgical.com/en/forensic-medicine/the-duty-to-report-a-crime-and-its-limits/)
- [The rural doctor (SSO) as forensic examiner](https://durgical.com/en/forensic-medicine/the-rural-doctor-as-forensic-examiner/)

## Connections

## Related 5

- [The limits of confidentiality: duty to warn and legal disclosure](https://durgical.com/en/medical-ethics/the-limits-of-confidentiality-duty-to-warn-and-legal-disclosure/)
- [Fidelity and dual loyalty](https://durgical.com/en/medical-ethics/fidelity-and-dual-loyalty/)
- [Medical certificates: sick leave, death and medico-legal reports](https://durgical.com/en/medical-ethics/medical-certificates-sick-leave-death-and-medico-legal-reports/)
- [Mandatory reporting: public health, violence and abuse](https://durgical.com/en/medical-ethics/mandatory-reporting-public-health-violence-and-abuse/)
- [Professional secrecy and confidentiality](https://durgical.com/en/medical-ethics/professional-secrecy-and-confidentiality/)

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Educational content on ethics and health law; not legal advice. Laws and case law change: each page links the official text and says when it was last checked. For a real case, read the text in force and ask a lawyer or the medical ethics tribunal.

Sources: [Ley 906 de 2004, Code of Criminal Procedure, arts. 56, 385 and 411](https://www.funcionpublica.gov.co/eva/gestornormativo/norma.php?i=14787) (Función Pública, Gestor Normativo, 2004); [Ley 23 de 1981, art. 1, item 6](https://www.funcionpublica.gov.co/eva/gestornormativo/norma.php?i=68760) (Función Pública, Gestor Normativo, 1981); [WMA International Code of Medical Ethics (2022), paras. 8 and 23](https://www.wma.net/policies-post/wma-international-code-of-medical-ethics/) (World Medical Association, 2022).

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Source: https://durgical.com/en/medical-ethics/treating-doctor-and-expert-witness-two-roles-that-do-not-mix/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/medical-ethics/treating-doctor-and-expert-witness-two-roles-that-do-not-mix/