The conflict between patients' needs for confidentiality and the public need for information has existed throughout history. In addition, in both ethics and modern law many more health professionals than just physicians are bound to respect the confidentiality of others. Laws currently exist regarding protection of the confidentiality of personally identifiable results of mandatory and voluntary blood testing, reporting of AIDS cases and sometimes of positive HIV tests to public health authorities, and contact tracing. Confidential laws also relate to research to determine the prevalence of HIV infection and disclosure of confidential information in the course of legal proceedings. Judicial decisions also indicate that certain situations may make it the duty of health professionals to warn unaware potential victims of HIV infection. In addition, one decision has also asserted that health professionals in certain cases have the legal power to warn as an exception to legislation mandating confidentiality.