As he is an official member, he has diplomatic immunity and can't be arrested by the host country. The most they can do is send them back to their home country as persona non grata.
The famous public speech delivered by Martin Luther King calls for ending racism in the United States. It was delivered in 1963 in the steps of the Lincoln memorial in Washington.
"Head and Master" laws were a set of American property laws where the husband was able to make a decision without the wife's consent or knowledge. They started repealing this law up until 1979, when Louisiana was the last state to get rid of it.
It must be very difficult to decide which country to invite, but usually this is decided based in economic or political interest. Based on this, it is no wonder the countries invited most times are the UK and France.
This happened on November 3rd, 1948, as the Chicago Daily Tribune had to send to print before all votes were counted. Truman himself was handed a copy while on his way to Washington. And actually other newspapers also had similar mistakes, but at least not on the front page.
In came in a perfect moment when the goal of his campaign was to re-unify a deeply divided country.
He was also a professional football player. All of this during the 1920s and 1930s. Oh, he was also a politician who won a seat in the House of Commons.