Is promotion of contraception a reason to excommunicate? Melinda Gates (wife of Bill Gates) promotes contraception such as condoms and sterilization among many other things. This is against the Catholic teaching. She also claims to be a practicing catholic. 

My question is: Could public promotion of something that is against the teaching of the Catholic Church be used to excommunicate? If yes, why doesn't the Catholic Church excommunicate her? Or who/where can claim the case for excommunication?
Canon 915 states:


  Those who have been excommunicated or interdicted after the imposition or declaration of the penalty and others obstinately persevering in manifest grave sin are not to be admitted to holy communion.


Those who publicly promote contraception are "persevering in manifest grave sin". It's manifest because it's public; it's grave because sexual sins are always grave matter.




  Could public promotion of something that is against the teaching of the Catholic Church be used to excommunicate?


Yes


  If yes, why doesn't the Catholic Church excommunicate her?


Cowardly bishops


  Or who/where can claim the case for excommunication? 


Bishops can excommunicate.