The Cortes of Castile and León were the devolved, unicameral legislature of the autonomous community of Castile and León, having legislative power in regional matters as defined by the Spanish Constitution and the Castilian-Leonese Statute of Autonomy, as well as the ability to vote confidence in or withdraw it from a President of the Junta. Voting for the Cortes was on the basis of universal suffrage, which comprised all nationals over eighteen, registered in Castile and León and in full enjoyment of their political rights. Additionally, Castilian-Leonese people abroad were required to apply for voting before being permitted to vote, a system known as "begged" or expat vote. All members of the Cortes of Castile and León were elected using the D'Hondt method and a closed list proportional representation, with a threshold of 3 percent of valid votes—which included blank ballots—being applied in each constituency. Parties not reaching the threshold were not taken into consideration for seat distribution. Additionally, the use of the D'Hondt method might result in an effective threshold over three percent, depending on the district magnitude. Seats were allocated to constituencies, corresponding to the provinces of Ávila, Burgos, León, Palencia, Salamanca, Segovia, Soria, Valladolid and Zamora. Each constituency was entitled to an initial minimum of three seats, being allocated one additional member per each 45,000 inhabitants or fraction greater than 22,500. The electoral law provided that parties, federations, coalitions and groupings of electors were allowed to present lists of candidates. However, groupings of electors were required to secure the signature of at least 1 percent of the electors registered in the constituency for which they sought election. Electors were barred from signing for more than one list of candidates. Concurrently, parties and federations intending to enter in coalition to take part jointly at an election were required to inform the relevant Electoral Commission within ten days of the election being called.
Election date
The term of the Cortes of Castile and León expired four years after the date of their previous election, unless they were dissolved earlier. The election Decree was required to be issued no later than the twenty-fifth day prior to the date of expiry of parliament and published on the following day in the Official Gazette of Castile and León, with election day taking place on the fifty-fourth day from publication. The previous election was held on 22 May 2011, which meant that the legislature's term would have expired on 22 May 2015. The election Decree was required to be published no later than 28 April 2015, with the election taking place on the fifty-fourth day from publication, setting the latest possible election date for the Cortes on Sunday, 21 June 2015. The President of the Junta had the prerogative to dissolve the Cortes of Castile and León and call a snap election, provided that no motion of no confidence was in process and that dissolution did not occur either during the first legislative session or before one year had elapsed since a previous dissolution. In the event of an investiture process failing to elect a regional President within a two-month period from the first ballot, the Cortes were to be automatically dissolved and a fresh election called.
Opinion polls
The table below lists voting intention estimates in reverse chronological order, showing the most recent first and using the dates when the survey fieldwork was done, as opposed to the date of publication. Where the fieldwork dates are unknown, the date of publication is given instead. The highest percentage figure in each polling survey is displayed with its background shaded in the leading party's colour. If a tie ensues, this is applied to the figures with the highest percentages. The "Lead" column on the right shows the percentage-point difference between the parties with the highest percentages in a given poll. When available, seat projections are also displayed below the voting estimates in a smaller font. 43 seats were required for an absolute majority in the Cortes of Castile and León.
