Jurisdiction: united-kingdom
First, I quote Maurice Sunkin's Public Law Text Cases Materials (4th edn, 2019), page 34.
Withholding
Royal Assent (for example, because the Queen had a moral objection to something in the bill)
would be undemocratic. Conclusion: there is a convention.31
31 Matters may be somewhat more complicated. If you want to delve deeper, see N.W. Barber, ‘Can Royal
Assent Be Refused on the Advice of the Prime Minister?’, UK Constitutional Law Blog, 25 September 2013,
http:// ukconstitutionallaw.org.
I quote Keith Ewing, Constitutional and Administrative Law (18th edn, 2022), pages 21-2.
The
monarch’s legal power to refuse Assent was last exercised by Queen Anne in 1708, when
(apparently with the approval of her ministers and without objection by Parliament) Assent
was refused to the Scottish Militia Bill.120 In the Irish crisis of 1912–14, the Unionists suggested
to George V that he should withhold Assent from the Bill to give home rule to Ireland.
The Liberal Prime Minister, Asquith, advised the King against this and the Royal Assent
was granted.121 While the Queen may not of her own initiative refuse the Royal Assent, the position might be different if ministers advised her to do so, although this advice would have
to be defended in Parliament and, depending on the circumstances, could be highly controversial.
122
120 Hearn, The Government of England, p 61.
121 Jennings, Cabinet Government, pp 395–400. Cf Brazier, Constitutional Practice, pp 193–6. See too:
Twomey, The Veiled Sceptre.
122 The highly acclaimed 2014 play by Mike Bartlett, Charles III, has as its premise King Charles III exercising
his refusal of Assent to a Bill limiting press freedom, with significant consequences. A real-world
example arose in the fraught process of negotiations with the EU over withdrawal, when Parliament twice
passed primary legislation obliging the Government to seek an extension of membership which it did not
wish to seek (see ch 6). Could the Prime Minister constitutionally have advised the Queen to refuse the
Royal Assent to such Bills? It is well arguable that such advice could have been given, although whether
the Queen was then bound to accept that advice – contrary as it would have been to the expressed wishes
of both Houses of Parliament – is a further vexed question. The obvious and considerable constitutional
ramifications of such steps have usually caused politicians to avoid such questions having to be asked, and
it is a testament to the political tensions over Brexit that they were more seriously considered than at any
time in recent history.