Should You Use Commas, Yes or No?

Comma Rule #4
Place commas around non-essential (or non-restrictive) words, phrases, or clauses (that interrupt the main clause or sometimes end the main clause).

Ask Yourself:

1. Does the adjective clause begin with that? —Yes?  Then use no comma.
 
Athletes should eat foods that are high in complex carbohydrates.
 
2. Does the adjective clause begin with which? — Yes?  Then put commas around the whole adjective clause.
 
Her hobbies, which included rock climbing and camping, led to her career as a forest ranger.
 
3. Does the adjective clause begin with one of the who words? —Yes?  Then sometimes you use commas and sometimes you don’t.
 
1. Do you absolutely need the adjective clause to determine which person the sentence is about? —Yes?  No comma.
 
The boy who lives across the street has a crush on my daughter.
 
2. Is the antecedent a proper noun (a name)? —Yes?  Then put commas around the whole adjective clause.
 
James Savage, who was my Shakespeare professor, won the bass fishing rodeo for five years in a row.
 
3. Is there a sense of "allness" surrounding the antecedent and the adjective clause? —Yes?  Then put commas around the whole adjective clause.

 
• Politicians, whom I distrust, sacrifice integrity for power.  [meaning with commas: I distrust all politicians, and all politicians sacrifice integrity for power.]
• Politicians whom I distrust sacrifice integrity for power.  [meaning without commas: I distrust some politicians, and those particular politicians sacrifice integrity for power.]