If you want to read a classic insider narrative of the degeneration and dysfunction of a large and powerful (and unlimited) federal bureaucracy, read here: http://www.nationalreview.com/article/443227/consumer-financial-protection-bureau-tragic-failures.  The article chronicles the work of one highly placed lawyer in the Consumer Financial Protection Bureau  before it was slapped hard by the Federal courts.

I have frequently written about what can and does occur when Constitutional limits are ignored.  This is all too frequent, given the propensity of Congress to simply give up its legislative authority to agencies and to allow them to operate with a more or less free hand.  The original purpose of the CFPB was to supplement the market by incentivizing greater information for consumers (whether that was necessary or not we can debate, but it did have a meritorious goal), but it quickly devolved into an imperial monstrosity, as you will see.