Cisco ASA Security Levels

So I just discovered that the Cisco ASA’s in their documentation refer to security levels and that higher security levels have access to lower security levels.  A few months ago I was playing with a Cisco ASA and using the firewall functionality. By defining one firewall rule on the Cisco ASA it negates the security level functionality.

If you define one firewall rule, you will need to specify all allowed traffic through firewall rules.