Dropping the writ is the informal term for a procedure in some parliamentary government systems, where the head of government (that is the prime minister, premier or chief minister, as the case may be) goes to the head of state and formally advises him or her to dissolve parliament. By convention, the head of state grants the request and issues writs of election for new members of parliament. The usage of the word "drop" in this context is likely derived from the phrase "draw up".
The head of state usually has the right to refuse the request, in which case the prime minister is required by convention or statute to resign. For example, in the case of a minority government, the head of state can deny the request for dissolution and ask the leader of another parliamentary party to form a government. In some cases, such as with the President of Ireland, there are specific limitations on when a head of state can refuse this request. Even under these circumstances, this right is rarely exercised, as it is likely to precipitate a constitutional crisis (see, for example, the King-Byng Affair of 1926) – it is possible that this right, of a head of state to refuse a dissolution, has become a lapsed power. However, there is a more recent counter-example in the 1985 election in Ontario. The incumbent Progressive Conservative party was reduced to minority status, and lost a non-confidence motion. Lieutenant Governor John Black Aird asked the opposition Liberal leader to form a government, with third-party NDP support, rather than issuing new writs of election.