Taken straight from the church's mouth (so now you can read it for yourself rather than keep pm'ing me):
In her statement to the House of Commons on 11th December on the Government's proposals for Equal Marriage, the Secretary of State said:
"because the Church of England and Wales have explicitly stated that they do not wish to conduct same-sex marriages the legislation will explicitly state that it would be illegal for the Churches of England and Wales to marry same-sex couples. Mr Speaker, this provision recognises and protects the unique and Established nature of these churches. The church's canon law will also continue to ban the marriage of same-sex couples. Therefore, even if these institutions wanted to conduct same sex marriage, it would require a change to primary legislation at a later date and a change to canon law. Additional protection that cannot be breached."
Press and political commentary on this has given rise to the impression that extra safeguards have been put in place for the Church of England, which give legal protection above and beyond that for other denominations and faiths. Some have said that this amounts to Government deciding to give preferential treatment to the Church of England on the question of legal protection for religious organisations not wishing to perform same-sex marriages. Others have questioned why the Government should explicitly write in to primary legislation that it would be "illegal" for the Church of England to perform same sex marriages when it will not be so for other denominations and faiths, taking this to mean that it places additional legislative barriers in the way of the Church of England in the unlikely event that it should wish to change its current position.
Such questions are understandable, but are based on a misunderstanding of the Church of England's established status and its relationship with Parliament on matters relating to Canon Law.
This is not a question of the Government and Parliament imposing a prohibition or "ban" on what the Church of England can do. It is instead the Government responding to the Church's wish to see the status quo for the Church of England preserved and accepting, as for other churches and faiths (though the legal framework is different for them), that it is not for the Government and Parliament to determine matters of doctrine.
As explained in the Church of England's submission to the Government's consultation in June 2012 (here: http://tinyurl.com/bsn6dxt ), the Canons of the Church of England define marriage, in accordance with Christ's teaching and the doctrine of the Church, as being between a man and a woman. Because the Canon Law of the Church of England is also part of the public law of the land and cannot be in conflict with statute law, it is important that any legislation for same-sex marriage makes it clear that it does not apply to marriage according to the rites of the Church of England. The legislative drafting of what is needed for the Church of England is necessarily unique because of that; and because Church of England clergy normally have a legal duty to marry people by virtue of their office. The Government, in accepting that the legal effect of the Canons of the Church of England need to be preserved (in line with its assertions about protection of religious liberty), have committed to drafting legislation on same sex marriage accordingly.
The effect of what the Government has proposed is to leave decisions about the doctrine and practice of the Church of England with the Church of England. Any change to the Church of England's doctrine and practice of marriage would require legislation by the Church's General Synod. In addition to an Amending Canon that redefined the nature of marriage such a legislative package would also involve the General Synod passing a Measure (the General Synod's equivalent of an Act of Parliament) that altered both the statute law concerning marriage according to the rites Church of England and the marriage service in the Book of Common Prayer.
All Synod Measures require parliamentary consent. The usual process of parliamentary scrutiny for legislation submitted by the Church is that it goes first to the Ecclesiastical Committee and then has a single debate in each House before the Measure goes for Royal Assent. As the General Synod's devolved legislative powers includes the ability to amend Westminster legislation it would not require separate, additional legislation on the part of Parliament to enact any change to the Church's practice on marriage. Talk of additional 'barriers to opt-in' for the Church of England following the Secretary of State's announcement is therefore misplaced.
For Parliament to give the Church of England an opt-in to conduct same sex marriages that it hasn't sought would be unnecessary, of doubtful constitutional propriety and introduce wholly avoidable confusion.
In addition, as the Bishop of Leicester said in the House of Lords on 11th December in response to the Government statement "our concern here is not primarily for religious conscience or the protection of the Church of England's position, but rather a more fundamental concern for stable communities". The arguments set out in the Church of England's submission in June to the Government's consultation (here:http://tinyurl.com/bsn6dxt) spell out those concerns in detail.