I read somewhere, that prepositions must take the objective case and not the nominative case. I had made a note of this in my flashcard, however can someone tell me if this is true? I can't find the source right now...so your help will be appreciated.

Take the following for example;
"Every conservative except smith and she was defeated"
is the above statement correct as is ? or should it be "except Smith and She"...This doesnt sound correct if i follow the rule.

Another example;
"Everyone on both sides except the pitcher and me was injured in that game"- is this correct?

Thanks.