Sicurella v. United States (1955) overturned the conviction of a Jehovah’s
Witness who was refused conscientious objector status. The First Amendment
protects such objectors.

United States v. Macintosh (1931) rejected that the First Amendment’s
protection of conscientious objectors extended to those applying for
citizenship.

In 1965, the Supreme Court expanded the concept of religion that is
protected under the First Amendment in a case involving a conscientious
objector who did not believe in a single Supreme Being. In United States v.
Seeger, the Court moved away from requiring a theistic belief to qualify
for protection of religious freedom.

In a case about religious exemptions from the military draft, Welsh v.
United States (1970) sought to define the meaning of religion under the
First Amendment.

In Clay v. United States (1971) rejected a denial of conscientious objector
status to Cassius Clay. “Right to conscience” is protected by the First
Amendment.

In a case that offers insight into how early American courts viewed liberty
of conscience, the Pennsylvania Supreme Court upheld a judge’s decision to
remove a juror who opposed the death penalty. In Commonwealth v. Lesher
(1828), the court questioned how a judge could have forced a juror to “take
the affirmation, which in his own heart he was determined to disregard.”

In Gilbert v. Minnesota, the Supreme Court upheld the conviction of Joseph
Gilbert for criticizing conscription and U.S. participation in World War I.

In Gillette v. United States, the court denied a draft exemption to a man
who refused to participate in the Vietnam War but would have fought in a
war of self defense.

In Girouard v. United States, the Supreme Court held that citizenship
applicants do not have to swear they will bear arms if they have religious
objections.