Much debate has arisen in the United States among physicians, religious leaders, lawyers, and the general public over the question of what constitutes actively causing death and what constitutes merely allowing death to occur naturally. The physician is faced with deciding whether measures used to keep patients alive are extraordinary in individual situations, e.g., whether a respirator or artificial kidney machine should be withdrawn from a terminally ill patient. The Supreme Court's decision in Cruzan v. Director, Missouri Dept. of Health set a precedent for the removal of life-support equipment from terminal cases.

Popular movements have supported the legalization of the living will, a statement written by a mentally alert patient that can be used to express a wish to forgo artificial means to sustain life during terminal illness. In 1977, California became the first to pass a state law to this effect, known as the death-with-dignity statute. The absence of a written living will complicated the case of Terri Schiavo, a Florida woman who was in a persistent vegetative state from 1990 until 2005, when she died after having her feeding tube removed. In 2000 her husband, who was her legal guardian, won the right to remove it based upon what he stated were her orally expressed wishes, but legal challenges from her parents and Florida governor Jeb Bush and attempted government interventions through Florida and federal legislation delayed the tube's removal for five years. (See Schiavo case.)

Societies advancing the cause of positive euthanasia were founded in 1935 in England and 1938 in the United States. End-of-Life Choices (formerly the Hemlock Society) is one controversial group that has pressed for right-to-die legislation on a national level. Positive euthanasia is for the most part illegal in the United States, but physicians may lawfully refuse to prolong life when there is extreme suffering.

In the early 1990s, Dr. Jack Kevorkian, a Michigan physician, gained notoriety by assisting a number of people to commit suicide and became the object of a state law (1992) forbidding such activity. Kevorkian, who had been tried and acquitted repeatedly in the assisted deaths of seriously ill people, was convicted of murder in Michigan in 1999 for an assisted suicide that was shown on national television. Meanwhile, in 1997, the Supreme Court upheld state laws banning assisted suicide (in most U.S. states assisting in a suicide is a crime). In Oregon in 1994, voters approved physician-assisted suicide for some patients who are terminally ill; the law went into effect in 1997, following a protracted court challenge. In 2001 the Bush administration sought to undermine the law with a directive issued under the federal Controlled Substances Act, but Oregon sued to prohibit the enforcement of it, and the Supreme Court ruled (2006) that the federal government had exceeded its authority. Voters in Washington state approved a similar measure in 2008.

Since 1937 assisted suicide has not been illegal in Switzerland as long as the person who assists has no personal motive or gain. In 1993, the Netherlands decriminalized, under a set of restricted conditions, voluntary positive euthanasia (essentially, physician-assisted suicide) for the terminally ill, and in 2002 the country legalized physician-assisted suicide if voluntarily requested by seriously ill patients who face ongoing suffering. Belgium has also legalized (2002) euthanasia for certain patients who have requested it.

See also bioethics.