America is in fact one of the most transparent nations on earth. [1] That includes the judiciary, presidency, congress, and law structure. The US Government and state governments publish vast amounts of information about their operations, studies, results, bills, spending, research, etc that is publicly available. The US routinely scores among the top few nations when it comes to making such data public.
It's also widely regarded as one of the least corrupt nations. [2] Transparency and low-corruption are two things that very frequently go hand-in-hand.
[1] http://www.usnews.com/news/best-countries/transparency-full-...
"Denmark [the US came in #11] is the most transparent country, according to more than 8,000 informed elites from four different regions who filled out surveys for the 2016 Best Countries rankings. The rankings, formed in partnership with brand strategy firm BAV Consulting and the Wharton School of the University of Pennsylvania, aim to gauge global perceptions of the world's biggest economies in terms of specific attributes associated with countries."
On corruption the US is listed at #16 by transparency international, ahead of France and Japan, but behind Australia and the UK:
[2] http://www.transparency.org/cpi2015#results-table