In a Democratic Common Law-based governing system, the Head of State is the most senior public servant in the land and they have many important functions - but one of these is more important than any other.
Before stating what it is, we need to understand that all legislation that is proposed in the legislature (Parliament) in the form of Bills has to come before the Monarch to be ratified.
This mechanism is called Royal Assent
in Britain. Importantly, however, the Monarch has the power to refuse
that assent to a Bill of parliament, meaning they can block it. When people first hear about this, they often feel edgy and irritated, because they feel that this would be blocking the will of our 'representatives'. But it is meant to be there as a protection mechanism. Think about it...
The Monarch's most important role is to prevent the formation of legislation that infringes on the rights and liberties of the people and on the constitution.
It is to prevent too much power coming from politicians
! Given that most people rightly don't trust politicians - maybe this is a good thing!
Now the powers-that-be will claim - as in fact they do on the parliament website - that, whilst the King or Queen has the power to refuse assent, they wouldn't do this because it is now regarded as a mere formality. Decided by who exactly?
Parliament cannot write itself into constitutional authority
Remember, that this is how the constitution was set-up to work. They are disregarding it and are getting away with it. Why? Because we, the people, aren't owning the constitution and defending it. We haven't cared enough!