"Researchers from Princeton University and Northwestern University have concluded, after extensive analysis of 1,779 policy issues, that the U.S. is in fact an oligarchy and not a democracy. What this means is that, although 'Americans do enjoy many features central to democratic governance,' 'majorities of the American public actually have little influence over the policies our government adopts.' Their study (PDF), to be published in Perspectives on Politics, found that 'When the preferences of economic elites and the stands of organized interest groups are controlled for, the preferences of the average American appear to have only a minuscule, near-zero, statistically non-significant impact upon public policy.'"
(from ./)

the study link:

https://www.princeton.edu/~mgilens/Gilens%20homepage%20materials/Gilens%20and%20Page/Gilens%20and%20Page%202014-Testing%20Theories%203-7-14.pdf