Helsinki 50 years on.

Ever since its adoption the Declaration of Helsinki has been universally recognised as a key landmark in the ethics of medical research involving human subjects. Over fifty years it has been revised seven times and supplemented twice with explanatory notes. The debate surrounding its contents and organisation continues unabated and becomes particularly lively every time the text is reviewed. One of the most controversial issues is recourse to the placebo: the conditions laid down for its use are held by many to offer insufficient guarantees for the protection of those receiving it.