1987 Castilian-Manchegan regional election

The Cortes of Castilla–La Mancha were the devolved, unicameral legislature of the autonomous community of Castilla–La Mancha, having legislative power in regional matters as defined by the Spanish Constitution and the Castilian-Manchegan Statute of Autonomy, as well as the ability to vote confidence in or withdraw it from a President of the Junta of Communities.[1] Voting for the Cortes was on the basis of universal suffrage, which comprised all nationals over 18 years of age, registered in Castilla–La Mancha and in full enjoyment of their political rights.

The 47 members of the Cortes of Castilla–La Mancha were elected using the D'Hondt method and a closed list proportional representation, with a threshold of 3 percent of valid votes[lower-alpha 2]—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.[2] Seats were allocated to constituencies, corresponding to the provinces of Albacete, Ciudad Real, Cuenca, Guadalajara and Toledo. Each constituency was entitled to an initial minimum of five seats, with the remaining 22 allocated among the constituencies in proportion to their populations.[1][3]

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.[3][4][5]

The term of the Cortes of Castilla–La Mancha expired four years after the date of their previous election. Election day was to take place between the thirtieth and the sixtieth day from the date of expiry of parliament and set so as to make it coincide with elections to the regional assemblies of other autonomous communities. The previous election was held on 8 May 1983, which meant that the legislature's term would have expired on 8 May 1987. The election was required to take place no later than the sixtieth day from the date of expiry of parliament, setting the latest possible election date for the Cortes on Tuesday, 7 July 1987.[1][3][4][5]

The Cortes of Castilla–La Mancha could not be dissolved before the date of expiry of parliament. In the event of an investiture process failing to elect a regional President within a two-month period from the first ballot, the candidate from the party with the highest number of seats was to be deemed automatically elected.[1]