Normalizing vs de-normalizing

I have a database with a [Cases] table and a [Defendants] table. There are usually about 40 defendants or so for every case. Here's the deal though: Sometimes I need to pull up a query that says
"show me all casenumbers where the defendant can be (Arco or Shell or
Exxon) AND the casenumber has to have defendant Union76.

This is a bit awkward for SQL if the Defendants table and Cases table are separate. I, at first, thought about keeping the tables separate and doing a series of queries that build upon each othre, but this method seems slow performance-wise. Another method I thought of is to DENOMARMALIZE the database and simply list all defendants per case in a single long text field within [Cases]. Then I can do all the
"ands" and "ors" in that text field without SQL awkwardness. Performance
seems fast too.

Do you think this is the best method or is there a better way?

• Steve