John, the British Empire ended slavery in 1833, quite some time before the USA did.

Yet, I would not hold the British up necessarily as paragons of human progress in a blanket sense (though they have made significant contributions)...nor would I regard them as above criticism...nor would I regard a Briton who criticized his society for its errors, past or present, as being somehow disloyal to Britain. Quite the contrary. But you seem to feel that "liberals" (as you interpret the word) are somehow disloyal to the USA.

It's all a matter of perception, isn't it? Which USA are they being disloyal to? Which vision OF the USA? Yours or theirs?

You cannot claim that the USA was historically at the "cutting edge" in ending slavery. It was not. The USA was a latecomer when it came to ending slavery. The USA also seems to have more troublesome issues between blacks and whites than most other developed societies, right to this day. (You certainly make more noise about it, that's for sure.) In what other country would a travesty like the O.J.Simpson trail occur? In what other country were race riots seen to equal those in Detroit, Watts, and Los Angeles? In what other country were people like Martin Luther King and Malcolm X raised up to lead mass movements of blacks fighting for equality and assassinated?

The USA has a tremendously traumatic history as a result of its historical adventure with the institution of slavery, and the damage from that is still experienced today by millions of people, both black and white. The fear and hatred are still there today.

I don't call that "cutting edge", unless you mean the edge of the knife that cuts the throat...