According to the Centre for Evidence-Based Medicine, "Evidence-based medicine is the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients."

Using techniques from science, engineering and statistics, such as meta-analysis of the existing literature, risk-benefit analysis, and randomized controlled trials, it aims for the ideal that all doctors and other healthcare professionals should make "conscientious, explicit, and judicious use of current best evidence" in their everyday practice.

Evidence-based medicine categorizes different types of clinical evidence and ranks them according to the strength of their freedom from the various biases that beset medical research. For example, the strongest evidence for therapeutic interventions is provided by randomized, double-blind, placebo-controlled trials involving a homogeneous patient population and medical condition. In contrast, patient testimonials, case reports, and even expert opinion have little value as proof because of the placebo effect, the biases inherent in observation and reporting of cases, difficulties in ascertaining who is an expert, and more.

Practising evidence-based medicine implies not only clinical expertise, but expertise in retrieving, interpreting, and applying the results of scientific studies, and in communicating the risks and benefit of different courses of action to patients.

For all its problems, evidence-based medicine has very successfully demoted the ex cathedra statement of the "medical expert" to the least valid form of evidence, and all "experts" are now expected to be able to reference their pronouncements to the relevant literature. One way that physicians facilitate the integration of evidence-based medicine in daily practice is via participation in a journal club.

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