Would imposing new/more tarrifs on foriegn goods help the economy?

[Asuras]

In the U.S. Glass-Steagal,

In the US:

Glass-Steagall did not affect interest rates or ROI, it was about the separation of investment banking from commercial banking. Glass-Steagall was passed in the 1930s and repealed in the late 1990s. Total ROI in America has exceeded 10% from 1945-1990. Chart to demonstrate:



Glass-Steagall was financial reform, sure. And strong financial reform. But I would contend that the effect was to increase ROI, investment, employment, productivity, and the standard of living over the long term. Those things all go together.

in Germany was their original Banking Law and its subsequent amendments (there were four or five), the transition from CEM to EU, and the Erstes, Zweites, und Drittes Finanzmarktforderungsgesetz ('90, '94, and '98) in conjunction with KWG-Novelles amendments.

I know German monetary policy. I don't know German financial law.  That's why I asked what law - why did these laws deter banks from pursuing profitable ventures (i.e, high ROIs). Names of German laws don't mean anything to me. What are these laws, and why are/were they good laws? What could possibly stop a bank from pursuing a profitable venture at the highest ROI (Glass-Steagall after all didn't, nor was it intended to) and why would such a law be a good thing?