[1] The number of seats in Parliament was raised from 550 to 600, while, among a series of other proposals, the president was given more control over appointments to the Supreme Board of Judges and Prosecutors (HSYK).

Three days before the referendum, one of Erdoğan's aides called for a federal system should the "Yes" vote prevail, causing a backlash from the pro-Yes MHP.

[13] Introducing a presidential system was proposed by then-Minister of Justice Cemil Çiçek and backed by then-Prime Minister Erdoğan in 2005.

[14] Since then, the current presidential system has been openly supported by Justice and Development Party leaders several times, along with a "new constitution".

[16] On 10 December 2016, the AKP and MHP brought forward a total of 21 proposed amendments to the constitution and began collecting signatures from MPs in order to begin the parliamentary procedures for initiating a referendum.

[20][21] After being signed by the AKP's 316 MPs, the 21 proposed changes were submitted to the Speaker of the Grand National Assembly and were then referred to the Parliamentary Constitutional Commission.

[22] The Parliamentary Constitutional Commission, headed by AKP MP Mustafa Şentop, began scrutinizing the proposals in December 2016, earlier than the planned date of January 2017.

Since the AKP held a large majority of the commission's seats, it was expected by media commentators that there would be minimal surprise developments at the scrutiny stage.

The Commission made minor changes to numerous proposals, such as raising the number of members of the Supreme Board of Judges and Prosecutors from 12 to 13.

[41] On 4 December, the Atatürkist Thought Association (ADD), Association for the Support of Contemporary Living (ÇYDD) and the Trade Union Confederation held a rally in Ankara despite having their permissions revoked by the Governor of Ankara, calling for a rejection of the executive presidential system on the grounds that it threatened judicial independence and secular democratic values.

[42] The amendments were initially received with mixed responses from the opposition CHP, which have long been critical of the AKP's constitutional plans.

[43] However, reception by the CHP was negative, with the party's deputy leader Selin Sayek Böke claiming that the proposals essentially created a "sultanate".

[45] Another of the CHP's parliamentary group leaders, Özgür Özel, called the proposals a "regime change", with the parliament being left essentially powerless in scrutinising ministers and holding them to account.

[47] CHP MP Selina Doğan claimed that the authoritarian nature of the proposals would effectively end Turkey's EU accession negotiations, citing the lack of any relevance to European values.

[54] Ümit Özdağ, who was a leadership candidate against Bahçeli and one of the 5 MPs critical of the changes, had his party membership revoked in November.

"[64] The Venice Commission of the Council of Europe, in its March 2017 Opinion on the Constitutional amendments, defined them as "a threat to democracy" and stressed the "dangers of degeneration of the proposed system towards and authoritarian and personal regime".

[65] Also, before the vote took place, the openDemocracy website reported that some European news outlets published concerns that the 2017 referendum amounted to something like an "enabling act" for Erdoğan.

[13] The AKP government and the General Directorate of Security (police) have both been criticized for employing tactics designed to limit the campaigning abilities of "No" supporters, through arrests, control of the media and political suppression.

On 23 January 2017, university students campaigning for a "No" vote on a commuter ferry in Istanbul were implicated by security officers for 'insulting the president', with their arrests being stopped by onboard passengers.

[174] On 31 January, Republican People's Party council member Sera Kadıgil was arrested and later freed on charges of 'insulting religious values and inciting hatred' for campaigning for a "No" vote on social media.

[64] A Turkish court banned a pro-Kurdish Peoples' Democratic Party (HDP) song Bejin Na (Say No) which supported the "No" on the grounds that it contravened the constitution and fomented hatred.

[177][178] Municipalities held by pro-"Yes" parties have also sought to limit the campaign events of "No" voters by denying them rights to hold rallies in public spaces of community halls.

[179][180] On 11 February while she was making a speech at a hotel hall in Çanakkale, the venue suffered a power cut and was perceived by the pro-opposition media to be a symbol of the oppressive tactics against the "No" campaign.

[188] Turkish foreign minister Mevlüt Çavuşoğlu claimed that Germany had showed 'double standards' and a disregard for 'human rights and freedom of speech' by cancelling the events.

[189] The Turkish government also accused Germany of funding and supporting the Kurdistan Workers Party (PKK), which is designated as a terrorist organisation in both countries.

[192] A diplomatic crisis occurred between Turkey and the Netherlands on 11 March, after Çavuşoğlu's official plane had its permission to land revoked mid-air ahead of a scheduled campaign speech.

Later that day, Families and Social Policy Minister Fatma Betül Sayan Kaya's convoy was stopped by Dutch police, which blocked her access to the Turkish consulate in Rotterdam.

[196] All CHP overseas campaign events were later suspended in solidarity, while the pro-"No" MHP dissident camp also expressed their condemnation against the Dutch government for their actions.

[199] On the referendum day, while the voting was underway, the Supreme Electoral Council of Turkey lifted a rule that required each ballot to have an official stamp.

[203] The Peoples' Democratic Party contested the election results announced by pro-government Anadolu Agency and insisted that 2.5 million votes without valid stamps should be cancelled.