Intervention is an action
- (Law) by which a third person who may be affected by a lawsuit is permitted to become a party to the suit.
- (Medicine) by which a person or persons or community at risk of danger to health and well-being, or in danger of death, receives preventive or restorative care toward alleviation of a physiological threat or distress, or toward effecting a cure. The CDC and the FDA intervene with measures and legislation implementing restrictive legal controls or prohibitions when they discover evidence of danger to public health; the DEA is tasked with enforcing relevant legislation. Abortion is also an intervention to terminate the life of a helpless infant, at any time before or immediately after birth.
- (Military) by which forces are deployed to effect a rescue of those in harm's way, or to effect change in current or impending military or political threats to local, national, international security. Border incursions, invasions, and internal coups are normally deemed by the international community of nations as unjust interventions in the internal affairs of a nation. The Korean War was an example of intervention by United Nations forces.
- (Civil government) by which police and detective and espionage activity on the basis of evidence intercepts and/or directly disrupts potential or actual plots to commit criminal activities, before, during or immediately after the damage threatened, occurring, or already done (to stop harm, or prevent further harm by the parties involved).
- (Political) by which actions overt or covert are taken to effect political change, as in correcting or corrupting elections or appointments legistative (government) or juridical (the courts), sometimes resulting in changes in law (just or unjust), or censure, or removal from office (just or unjust), or assassination. PACs constantly seek to intervene to protect their interests, not always for the benefit of the public safety, security, and general welfare. Among these is the controversial influence of the NRA which is both praised and vilified by other interest groups opposed or supporting.
- (Religion) by which intercessory prayer is made to God on behalf of those in need and in danger of harm, petitioning the Lord to intervene with help, to overthrow the evil and defend the innocent, weak and helpless.
- (individual) by which a single person (or group of persons) immediately acts in a timely manner to rescue someone in immediate danger of harm (such as tackling a man, woman, child to get them out of the way of a speeding vehicle, or stopping a bomber or gunman), and/or to save someone already seriously hurt by promptly effecting rescue operations (such as immediately administering CPR and calling for emergency services), or acts to alert authorities of a previously hidden situation of harm or threat or corruption within the community as soon as it is discovered.