The Eleventh Commandment
The eleventh commandment was a phrase used by Ronald Reagan to communicate the importance of not damaging members of the same Party. It was a very serious “joke” designed to encourage Republicans to support each other, or at least not to damage each other, and in turn not to damage the entire Republican Party.
The phrase really applies to members of any political party. However, it is particularly applicable to Republicans who have a notorious reputation for “eating their own” or abandoning each other, for a variety of reasons, when another Republican has made a mistake or is in trouble of some kind. Republicans have a reputation for having a much higher standard for behavior than Democrats have and are not considered to be as forgiving or supportive. Democrats have a reputation for “circling the wagons” and supporting each other in times of crisis. The strategy of the Democratic Party to support and protect each other is, generally speaking, more beneficial to the Party as a whole.
Note: The 10 Commandments are the 10 foundational laws from God, given the Israelites, which were written on stone tablets, and brought down from Mount Sinai by Moses. Both Judaism and Christianity describe this story and these laws in their religious texts.