In law school, we learned to be very careful with the use of commas.

The example we were given was a will where the individual wanted to give equal portions of his estate to his three children.

His will, however, said "... to my children Karen, Mike and Allen."

Karen later sued stating that she deserved fifty percent and the other two children deserved twenty-five percent each due to the placement/lack of a comma. Her claim was upheld. To give all three kids one-third, a comma between Mike and Allen was required.