Critics say the ruling on 'crossover' districts could reduce the political clout of minorities.
The move places the last remaining "enemy combatant" in the US before a civilian court instead of a military tribunal.
Lawyers for the Summum religion had argued that its monument should be allowed in a public park where the Ten Commandments were already displayed.
The justices rule that civil rights law protects a woman who was fired after answering questions in a harassment probe.
The decision will make it easier for local residents to recover damages from national firms, consumer groups say.
The case involves an ongoing tug of war between the high court and the highest court in Oregon.
The next president is expected to name at least one new justice to the closely divided court.
Key decisions of this term show a willingness of some justices to reject political leaders' judgments.
The move against the fundraising exceptions for wealthy candidates is the latest blow to McCain-Feingold reforms.
The Supreme Court cut Exxon's payment far more than many residents had expected.