Yes, the USA Patriot Act diminishes civil liberties, because it makes people fearful of their own government. The Patriot Act makes Americans think that the government is watching whatever they do. For the most part, they are right. The government is watching. Americans have fewer liberties in that just watching is reducing a civil liberty.
The USA PATRIOT Act most certainly does diminish civil liberties for Americans. If you read the history of this act, it was never supposed to be a permanent fixture on the American legal landscape because it does in fact interfere with liberty. The fact that it keeps getting reauthorized is a crime against the American people, and we should elect people to Congress who will vote against it.