The Oxford dictionary defines the term a cat may look at a king as meaning that even a person of low status has rights. Wiktionary defines the expression as meaning ”A purported inferior has certain abilities, even in the presence of a purported superior.”
The interesting www.idioms.in website has a longer treatment. This is an Indian website about idioms, and carries advertising. It also has a competition, Mention idioms.in on your blog and Win a Prize.
Here’s a better statement from another website, Writing Explained (Slogan: “Write better. Write now.”)
“A cat can look at a king is a proverb which implies that no matter how high your status is, you can’t control everything. Others will always be your equals in some way.” And I guess it might also have added, no matter how much the king resents it.
This idiom is first known in a 1562 collection of proverbs, The Proverbs And Epigrams Of John Heywood. Here is the full quote from the book
Some hear and see him whom he heareth nor seeth not
But fields have eyes and woods have ears, ye wot
And also on my maids he is ever tooting.
Can ye judge a man, (quoth I), by his looking?
What, a cat may look on a king, ye know!
My cat’s leering look, (quoth she), at first show,
Showeth me that my cat goeth a caterwauling;
And specially by his manner of drawing
To Madge, my fair maid.
The best-known use of the proverb is in Alice in Wonderland, in this passage which presents things from a king's viewpoint. Why should that cat be able to look at me?
"Who are you talking to?" said the King, coming up to Alice, and looking at the Cat's head with great curiosity. "It's a friend of mine–a Cheshire Cat," said Alice: "allow me to introduce it." "I don't like the look of it at all," said the King: "however, it may kiss my hand, if it likes." "I'd rather not," the Cat remarked. "Don't be impertinent," said the King, "and don't look at me like that!" He got behind Alice as he spoke.
Since then, of course, most of the world’s kings have fallen or faded, and been replaced by other figures of authority. Although the hereditary principle is far from gone, modern kings have chosen to assume other titles. But a cat can still look at them, whether they like it or not.
Resentment at being looked at by cats is perhaps one of the original inspirations for the legal concept lèse-majesté – see the Wikipedia for an explanation. These are the kinds of laws designed to stop cats from looking at kings just whenever they want to. And not just looking, either - once allowed to look at kings, cats may move on to even less acceptable actions. The hypersensitivity of contemporary rulers to contradiction, criticism, or failure to kiss the hand of a president or pope, has become a feature of our lives, but it is not new.
An article in Conservativehome, a UK journal for Conservatives, pointed out that the campaign to rescind the invitation to Donald Trump for a state visit to the UK was not based on his policies and actions as head of state, such as his ban on entry to the US people from certain predominantly Muslim countries. The article quotes from the petition and then makes a comment
"“Donald Trump should be allowed to enter the UK in his capacity as head of the US Government, but he should not be invited to make an official State Visit because it would cause embarrassment to Her Majesty the Queen.
“Donald Trump’s well documented misogyny and vulgarity disqualifies him from being received by Her Majesty the Queen or the Prince of Wales. Therefore during the term of his presidency Donald Trump should not be invited to the United Kingdom for an official State Visit.”
Such a marriage of left-wing gesture politics with a typically right-wing preoccupation with the dignity of the monarch is unusual, to say the least. Perhaps it’s an attempt to build broader support for a ban?"
Either way, there's no way a vulgar misogynist is going to be allowed to look at our Queen.