Duck wrote an opinion that a statute drafted by Laud for Wadham College, Oxford, was not ultra vires is mentioned in the Calendar of State Papers in 1625–6.
In 1639 he prosecuted a case against a false display of heraldry at a funeral of a wealth benefactor of Christ's Hospital.
[7] In 1641, Duck unsuccessfully contested the appointment of Sir William Meyrick as judge of the prerogative court of Canterbury.
Duck acquired the prebendal manor of Chiswick in Middlesex, held under a lease from St Paul's Cathedral in London.
[10] The Dictionary of National Biography records that Duck died in Chelsea in December 1648, and was buried at Chiswick in May 1649.
Duck wrote the following works:[11] According to one commentator, the Chichele biography was anti-papalist and negative about the foundations of canon law.