Why Can't the Church Ordain Women?
Why does the Church teach that women cannot be ordained when Jesus said, “Truly, I say to you, whatever you bind on earth shall be bound in heaven"?
The authority to bind and loose do not mean the pope and bishops can do whatever they want. The expression refers to forbidding or permitting certain things in relation to the commandments, but this does not apply to the actual commandments themselves. For example, the commandment is to keep holy the Sabbath. The particular things that are permitted or forbidden on the Sabbath are part of the authority to bind and loose, but the commandment itself cannot be done away.
The binding and loosing are referring to church laws, not divine laws. The difference between the two is so great that canon law refers to church laws as "merely ecclesiastical law" (can. 11). The Church is clear that its teachings on ordination come from divine law and not "mere" Church law.