The Coronation Oath Act 1688
(1 Will. & Mar., c. 6) was an Act of Parliament
of the Parliament of England
passed in 1689, the long title
of which is "An Act for Establishing the Coronation Oath". The preamble noted that "by the Law and Ancient Usage of this Realm" the monarchs of England had taken a solemn oath at their coronation
to maintain the statute laws and customs of the country and of its inhabitants, but the text of this oath had become partly meaningless over time, "framed in doubtful Words and Expressions with relation to ancient Laws and Constitutions at this time unknown". It established a single uniform oath to be taken by future monarchs at their coronation, and also established that this oath was to be taken by William
when they were crowned. The oath was shorter than the one used in 1660, removing a number of awkward phrases and references to past monarchs; perhaps the most significant alteration was the explicit inclusion of an oath to maintain "the true Profession of the Gospel and the Protestant Reformed Religion Established by Law", rather than the somewhat more vague promise to "Protect and Defend the Bishops and Churches under [my] Government."
- The Law & Working of the Constitution: Documents 1660-1914, ed. W. C. Costin & J. Steven Watson. A&C Black, 1952. Vol. I (1660-1783), p.57-9. (This includes a copy of the text of the oath as used in 1660, given for comparison)