A staunch conservative, Scalia was among the court's most polarizing figures, known for his pointed questions, bold disagreement and impassioned remarks. His opinions spanned seemingly every aspect of American life, from air quality and anti-abortion protests to life insurance, health insurance, deposit insurance plus prisons, phones and pharmaceuticals.
Former President George W. Bush called Scalia a "towering figure and important judge on our nation's highest court." In a statement late Saturday, Bush said the judge "brought intellect, good judgment and wit to the bench."
Scalia, who was 79, was reportedly found dead Saturday at a luxury resort in West Texas. He was appointed to the Supreme Court by former President Ronald Reagan and took his seat on the bench Sept. 26, 1986.
Here's a look at five of his most recent, and controversial, Supreme Court opinions:
1. Same-sex marriage
Scalia fiercely rejected the Supreme Court's 5-4 decision last June to legalize same-sex marriage across the country. In Obergefell v. Hodges, the court found that state-level bans on same-sex marriage were unconstitutional.
In his dissenting opinion, Scalia called the ruling a "threat to American democracy." He accused some of his fellow justices of acting like elected officials rather than the neutral arbiters they were supposed to be.
"Today's decree says that my Ruler, and the Ruler of 320 million Americans coast-to-coast, is a majority of the nine lawyers on the Supreme Court," he penned in his opinion. He said the decision "robs the people of the most important liberty they asserted in the Declaration of Independence and won in the Revolution of 1776: the freedom to govern themselves."
2. The Affordable Care Act
A day before the marriage ruling, Scalia was firing off a dissenting opinion about Obamacare – or as he called it, SCOTUScare.
In a 6-3 decision, the Supreme Court found in King v. Burwell that the federal tax credits that help nearly 6.4 million Americans pay for their health insurance plans are legal under the Affordable Care Act. The June 25 ruling effectively saved the controversial health law for the second time.
“We should start calling this law SCOTUScare,” Scalia wrote in his dissenting opinion. He argued the language of the Affordable Care Act clearly prohibited the subsidies, and he called the majority's argument "quite absurd" and "interpretive jiggery-pokery."
“The cases will publish forever the discouraging truth that the Supreme Court of the United States favors some laws over others, and is prepared to do whatever it takes to uphold and assist its favorites,” Scalia wrote.
3. Voting Rights Act
Scalia joined the majority opinion in striking down the heart of the Voting Rights Act of 1965. The 5-4 vote in June 2012 enabled nine states, mainly in the South, to revise their election laws without advance federal approval. Texas and other states soon proceeded with controversial voter identification laws.
Scalia had described key provisions of the Voting Rights Act as an "embedded" form of "racial preferment." The law was originally designed to protect against racial discrimination during the voting process. But Scalia and other judges argued it didn't reflect the "current conditions," as Chief Justice John Roberts wrote in the court's decision on Shelby County v. Holder.
"Whenever a society adopts racial entitlements, it is very difficult to get out of them through the normal political processes," Scalia said in 2013 in a speech at the University of California Washington Center. "Even the name of it is wonderful, the Voting Rights Act. Who's going to vote against that?"
4. Arizona immigration laws
Also in June 2012, Scalia voted to uphold key parts of an Arizona law to deter illegal immigration. He said Arizona's SB1070 policy would "protect its sovereignty – not in contradiction of federal law, but in complete compliance with it."
But Scalia was in the minority. The Supreme Court struck down those provisions in a 5-3 ruling. The court did let stand a controversial provision that allowed police to check a person's immigration status while enforcing other laws, like traffic violations.
Scalia said the court's decision on Arizona v. United States "boggles the mind" – particularly given that President Barack Obama was moving to end deportations of young adults brought into the country illegally. “If securing its territory in this fashion is not within the power of Arizona, we should cease referring to it as a sovereign state,” Scalia said.
5. Citizens United
Scalia joined the 5-4 majority in Citizens United v. Federal Election Commission, a critical decision that opened the spending floodgates for U.S. political campaigns. The justices' ruled that political spending is protected under the First Amendment, and therefore corporations and unions could spend unlimited amounts of money on political activities – so long as the spending is done independently of a party or individual candidate.
"I don't care who is doing the speech — the more the merrier," Scalia said during a 2012 presentation before the South Carolina Bar.
The court's decision has had a profound impact on the business of politics in the United States. An analysis of the 2014 Senate races found outside spending more than doubled since 2010, to $468 million, according to the Brennan Center for Justice. Outside groups provided nearly half of total spending – versus 41 percent from the candidates – in 10 competitive races in the 2014 midterms.
In the South Carolina presentation, Scalia had a simple solution for Americans who don't appreciate the wave of political advertisements now overtaking the airwaves during election season: change the channel, or turn off the TV. "People are not stupid," he said. "If they don't like it, they'll shut it off."