"…did not adhere to their look-back policies and procedures… compliance personnel were not aware of the statutory requirements. . did not detect multiple emails that contained market-share information and were sent to analysts which was prohibited… . appeared to have engaged in sales and marketing activities, which is prohibited… did not collect annual disclosures from its independent Board members."

These a few excerpts from the SEC's December 2015 re-examination of the Credit Ratings Organizations  (NRSROs) whose unethical behavior was a critical enabler the 2008 financial meltdown.  The dynamics that were at play before, are coming back.  As they are throughout the warp and woof of Wall Street.

During the fallout from the 1980s Savings & Loan scandal, over 1,000 felony convictions, largely bankers, were secured, at a conviction rate of 90%.  After the 2008 crisis, only a handful of low-level bank employees.

If the DOJ won't pursue criminal cases, what can Congress do ?

I would follow Bernie Sanders, and work for preventing Bankers from sitting on the boards of regulatory bodies that oversee them.  A stunning conflict of interest that should be ended.

Regulators should impose greater capital requirements on banks repeatedly accused of regulatory violations.

In "Better Bankers, Better Banks" Claire Hill and her co-author argue for "making financial executives personally liable for a portion of any fines and fraud-based judgments."

Also, with Hillary Clinton, I would work to re-enact derivatives-trading safeguards, that were recently repealed by Congress.

A bright spot: the CFPB.