The word "unless" (and words like until, without, or except) often appear in a confusing manner on the LSAT. Logically, these words introduce a necessary condition. HOWEVER, to diagram these statements, it is much easier to simply replace these words with the phrase IF NOT.
Ex. The team cannot win the championship UNLESS HE GETS ACQUITTED.
"If he is not acquitted, then the team cannot win a championship"
NOT acquitted → NO championship
Championship → Acquitted
Ex 2. UNTIL GRANDPA FINDS HIS TEETH, he won't be eating lunch.
If grandpa cannot find his teeth, then he won't be eating lunch
NO TEETH → NO LUNCH
Unless will occur in one of two ways;
1) unless A, B
2) B, unless A