Thislin wrote:
"A group of people cannot redefine words. This is the activity of lawyers who want to confuse the issues."

"A group of people" is exactly who does decide the meaning of words. I am old enough to remember when 'gay' meant ' very happy' and absolutely nothing else. It was also a popular girl's name, similar to Joy. "A group of people" changed the meaning almost overnight. There are many such examples, but this one of the most extreme, it happened very much more quickly than usual.

No meaning is set in stone, but we cannot individually decide on meaning or usage in a way binding on other people, partly because, as you suggest it would be legally meaningless. Lawyers do not re-define words, they merely challenge word meaning when the grammar or sytax allows for different interpretation. That is why, when we use a word, it should be carefully considered, terms should be defined with accuracy and the dictionary should be consulted frequently.