" should be upheld by all political parties. They should neither advise others to break the law, nor encourage others to do so even when they strongly disagree with the legislation put forward by the government of the day." Which phrase or term best fills the blank space at the start of this quote?

The rule of law

Explanation:

The rule of law is a legal power that states that a government has a power limited by the legislation of a country. This means that all government officials and the political body established in the country, are subject to the current legislation and have to strictly comply with it to continue in their positions. This prevents abuses of power, and protects citizens' rights and guarantees.

in other words, we can say that the rule of law must be supported by all political parties. They should not advise others to break the law, nor should they encourage others to do so, even when they strongly disagree with the legislation proposed by the government of the time.