US Catholic has an interesting article by Phyllis Zagano, “What’s the Problem with Women Deacons?” This article ably and succinctly summarizes the state of the question. Zagano makes clear that diaconate is a distinct order from the priesthood in the Catholic Church, and hence the question of ordaining women deacons is not connected to the question of women priests.
There are also some interesting nuggets in this piece. This, for example:
By all accounts, the ITC [International Theological Commission – ed.] voted to approve women deacons in a paper that its president, then-Cardinal Joseph Ratzinger, refused to promulgate. From 1997-2002 the ITC wrote a second study, about four times longer than the first, which said women deacons was a question for the Magisterium to decide. That is, they did not say no, they just did not say yes.
Read it here.