The regulators could not tell Warren the last time they took an institution to trial, and some argued it was not needed to to meet their responsibilities.
"We have not had to do it, as a practical matter, to achieve our supervisory goals," said Thomas Curry of the Office of the Comptroller of the Currency (OCC).
Following that hearing, she asked the OCC to provide any internal research that justified that position. The OCC responded that it had none.
Now Warren is asking the same question of the heads of other regulators charged with monitoring Wall Street.