Abood v. Detroit Board of Education (1977) said that requiring government
employees to pay union dues that weren’t used for political purposes did
not violate the First Amendment.

Chicago Teachers Union v. Hudson (1986) ruled a union’s dues collection
procedures were insufficient to protect First Amendment free association
rights.

In Harris v. Quinn (2014), the Supreme Court dealt with the First Amendment
issues of requiring personal care workers in Illinois to join a union
against their will.

Letter Carriers v. Austin (1974) ruled the term “scab” could not be the
basis of a libel claim by a non-union member as rhetorical hyperbole is
protected by the First Amendment.

Locke v. Karass (2009) said that as long as union litigation was related to
collective bargaining, charging nonmembers for national litigation did not
violate the First Amendment.

In 1957, the Supreme Court held that the use of general union treasury
funds to sponsor commercial television broadcasts touting 1954
congressional candidates was an indictable offense under 18 U.S.C. 610,
which banned corporate or labor contributions or expenditures in federal
campaigns.

In 1982, the Supreme Court upheld a federal law that prohibited candidates
for union leadership positions from accepting contributions from non-union
members in United Steelworkers v. Sadlowski. “Oilcan Eddie” Edward
Sadlowski had mounted a campaign for the presidency of the Steelworkers and
challenged the restriction.

In 1971, the Supreme Court reversed an injunction that prevented a union
from providing legal advice and services to members, saying it interfered
with the rights of association enjoyed under the First Amendment. In United
Transportation Union v. State Bar of Michigan, the Court pointed to its
previous rulings in union cases.