Modern bank regulation has two complementary parts: capital and liquidity requirements. The first  restricts liabilities given the structure of assets and the second limits assets based on the composition of liabilities.

While capital regulation―especially in its risk-based form―is a creation of the last quarter of the 20th century, liquidity regulation is much older. In fact, the newly implemented liquidity coverage ratio (LCR) harks back to the system in place over 100 years ago. In the United States, before the advent of the Federal Reserve in 1914, both national and state-chartered banks were required to hold substantial liquid reserves to back their deposits (see Carlson). These are the reserve requirements (RR) that remain in effect in most jurisdictions today, the United States included.   

In this post, we briefly examine the long experience with RR as a way to gain insight regarding the LCR. We draw two conclusions. First, we argue strongly against using the LCR as a monetary policy tool in advanced economies with well-developed financial markets. Like RR, it is simply too blunt and unpredictable. Second, for the LCR to work as a prudential policy tool, it should probably be supplemented by something like a fee-based line of credit at the central bank....