[1][7][8] He has said that as a teenager, he was briefly infatuated with the works of Ayn Rand, "[b]ut after about six weeks of enchantment, her books started to make me sick.

Anticipated areas of study include terrorism, climate change, occupational safety, infectious diseases, natural disasters, and other low-probability, high-consequence events.

[13]On January 7, 2009, The Wall Street Journal reported that Sunstein would be named to head the White House Office of Information and Regulatory Affairs (OIRA).

In his research on risk regulation, Sunstein is known for developing, together with Timur Kuran, the concept of availability cascades, wherein popular discussion of an idea is self-feeding and causes individuals to over weigh its importance.

Sunstein's books include After the Rights Revolution (1990), The Partial Constitution (1993), Democracy and the Problem of Free Speech (1993), Legal Reasoning and Political Conflict (1996), Free Markets and Social Justice (1997), One Case at a Time (1999), Risk and Reason (2002), Why Societies Need Dissent (2003), Laws of Fear: Beyond the Precautionary Principle (2005), Radicals in Robes: Why Extreme Right-Wing Courts Are Wrong for America (2005), Are Judges Political?

An Empirical Analysis of the Federal Judiciary (2005), Infotopia: How Many Minds Produce Knowledge (2006), and, co-authored with Richard Thaler, Nudge: Improving Decisions about Health, Wealth, and Happiness (2008).

Sunstein's 2006 book, Infotopia: How Many Minds Produce Knowledge, explores methods for aggregating information; it contains discussions of prediction markets, open-source software, and wikis.

His 2001 book, Republic.com, argued that the Internet may weaken democracy because it allows citizens to isolate themselves within groups that share their own views and experiences, and thus cut themselves off from any information that might challenge their beliefs, a phenomenon known as cyberbalkanization.

He cited the concepts of self-government and equal dignity of human beings, but focused in particular on stories: "an emphasis on what happened before and after the firing shots in Concord and the courageous response of the embattled farmers maintains continuity with the historical facts and offers us something on which we can build.

Drawing not least upon legal examples, it treats of unwanted variability in human judgments of the same problem, for instance when court judges recommend vastly different sentences for the same crimes.

Since 2021, Sunstein has co-taught a class on the United States Supreme Court at Harvard alongside retired Justice Stephen Breyer.

[29] Sunstein is a proponent of judicial minimalism, arguing that judges should focus primarily on deciding the case at hand, and avoid making sweeping changes to the law or decisions that have broad-reaching effects.

"[33] Much of his work also brings behavioral economics to bear on law, suggesting that the "rational actor" model will sometimes produce an inadequate understanding of how people will respond to legal intervention.

[citation needed] According to Sunstein, the interpretation of federal law should be made not by judges but by the beliefs and commitments of the U.S. president and those around him.

In arguing for this theory, he counsels thinkers/academics/politicians to embrace the findings of behavioral economics as applied to law, maintaining freedom of choice while also steering peoples' decisions in directions that will make their lives go better.

Sunstein scorned as "ludicrous" an argument from law professor George P. Fletcher, who believed that the Supreme Court would find Bush's military commissions without any legal basis.

He thinks that the current formulation, based on Justice Holmes' conception of free speech as a marketplace, "disserves the aspirations of those who wrote America's founding document.

"[38] He is concerned by the present "situation in which like-minded people speak or listen mostly to one another,"[39] and thinks that in "light of astonishing economic and technological changes, we must doubt whether, as interpreted, the constitutional guarantee of free speech is adequately serving democratic goals.

"[42] Sunstein's views on animal rights generated controversy when Sen. Saxby Chambliss (R-Ga.) blocked his appointment to the Office of Information and Regulatory Affairs by Obama.

Chambliss objected to the introduction of Animal Rights: Current Debates and New Directions, a volume edited by Sunstein and his then-companion Martha Nussbaum.

For example, under current law, if someone saw their neighbor beating a dog, they cannot sue for animal cruelty because they do not have legal standing to do so.

Rights to private property, freedom of speech, immunity from police abuse, contractual liberty, free exercise of religion – just as much as rights to Social Security, Medicare and food stamps – are taxpayer-funded and government-managed social services designed to improve collective and individual well-being.

[43]In Nudge: Improving Decisions About Health, Wealth, and Happiness, Sunstein proposes that government recognition of marriage be discontinued.

In this article they wrote, "The existence of both domestic and foreign conspiracy theories, we suggest, is no trivial matter, posing real risks to the government's antiterrorism policies, whatever the latter may be."

They go on to propose that, "the best response consists in cognitive infiltration of extremist groups",[45] where they suggest, among other tactics, "Government agents (and their allies) might enter chat rooms, online social networks, or even real-space groups and attempt to undermine percolating conspiracy theories by raising doubts about their factual premises, causal logic or implications for political action.

However, the authors advocate that each "instrument has a distinctive set of potential effects, or costs and benefits, and each will have a place under imaginable conditions.

However, our main policy idea is that government should engage in cognitive infiltration of the groups that produce conspiracy theories, which involves a mix of (3), (4) and (5)."

Sunstein and Vermeule also analyze the practice of recruiting "nongovernmental officials"; they suggest that "government can supply these independent experts with information and perhaps prod them into action from behind the scenes," further warning that "too close a connection will be self-defeating if it is exposed.