Adam Smith and universal opulence Adam Smith seems to be saying that the goal of governing is "universal opulence which extends itself to the lowest ranks of the people," which he appears to think achievable in capitalism with the minimalist government. Clearly, things did not work out the way he thought, prompting Karl Marx, 90 years later, to assert that state-protected capitalism is the legalization of thievery. What are some defenses economists make on behalf of Smith? References appreciated.
The irony of Marx's criticism is that Communism is just as, if not more, available to become a "legalization of thievery", due to the elimination of the "invisible hand" of the market. 

To your question, I would point to the Chicago School's consideration of Antitrust government intervention as a defense of the intuitions of Adam Smith, albeit a modification of strict faith in the ability for the "invisible hand" to unrestrictedly manage the fairness of the markets. 

Michael S. Jacobs discusses the rise of the Chicago School's antitrust perspective, in his 1995 article in the North Carolina Law Review, "An Essay on Normative Foundations of Antitrust Economics". For Chicagoans, Antitrust actions are a tool to protect the free market. This is aligned with Adam Smith's concept of economic systems, via the application of the strict guideline that "consumer welfare, narrowly conceived in explicit economic terms, should be the only object of inquiry" in considering antitrust intervention (Jacobs, 1995. e.g. Herbert Hovenkamp, 1985). These tools are only to be used with the strict attention to preserving efficiencies of the market - an allusion to the foundational premises of Smith. 

The topic of Antitrust Legislation provides an example of the role of government to intervene in the free market, while respecting the need for it to be enacted in a minimized way. 

Additional reference material can be found in the article - it is highly notated. 

LINK: "An Essay on Normative Foundations of Antitrust Economics". Michael S. Jacobs, North Carolina Law Review, 1995.