As far as I am aware bail outs are not "banned". There have been some changes in policy following the financial crisis of 2008-2009. The Dodd-Frank Wall Street Reform and Consumer Protection Act, passed in 2010, includes provisions designed to reduce the likelihood and impact of future financial crises. One example is the creation of the Orderly Liquidation Authority (OLA). This allows the government to intervene and wind down failing financial institutions in an orderly way, supposedly without relying on taxpayer-funded bailouts. The OLA is intended to prevent a repeat of the "too big to fail" scenario.

In addition to the OLA, Dodd-Frank also includes provisions that require banks to develop plans for their own resolution in the event of a crisis which are designed to ensure that troubled institutions can be wound down in an orderly way. For whatever that's worth.

There has been a shift towards the idea of "bail-ins" in some quarters. But, it's not really been tried on a large scale problem. The Jury is out on if it would help at all or just cause the contagion to spread quicker. I'm in the quicker camp but that's my $.02. lol.