In common English, "or" and "and" are often ambiguous. "Or" can mean either inclusive or exclusive or, among other things. "And" often means set union, which might correspond to either inclusive or exclusive "or" or logical "and." For example, "choose from a box containing X and Y" might mean "choose X or Y" (inclusive), "choose X or Y" (exclusive), or "choose X and Y" -- depending on whether you get to choose once, once or twice, or you must make two choices. There are any number of other ambiguities that arise when trying to deduce the logic, if any, behind many plain English uses of "and" and "or."
Nevertheless, it's not hard for a legal drafter to make the logic of a legal document clear. This should be Legal Drafting 101, a class which should be required in all law schools: use "X or Y, but not both" for exclusive or, "X or Y, or both" for inclusive or, "both X and Y" for logical and. It would probably save billions of dollars and many erroneous decisions per year if lawyers followed these three simple drafting tips. For that matter, technical writers and any other writers trying to make logical relationships clear might benefit from this advice.
Link here for a hilarious thread of some of America's smartest lawyers trying to decipher a Supreme Court opinion and decide whether it breaks one of De Morgan's Laws -- not (A or B) = not A and not B (where the "or" is inclusive). It may depend on what the meaning of "or" is.