The Cortes of Aragon were the devolved, unicameral legislature of the autonomous community of Aragon, having legislative power in regional matters as defined by the Spanish Constitution and the Aragonese Statute of Autonomy, as well as the ability to vote confidence in or withdraw it from a President of the Government. Voting for the Cortes was on the basis of universal suffrage, which comprised all nationals over eighteen, registered in Aragon and in full enjoyment of their political rights. The 67 members of the Cortes of Aragon 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 Huesca, Teruel and Zaragoza. Each constituency was entitled to an initial minimum of 13 seats, with the remaining 28 allocated among the constituencies in proportion to their populations on the condition that the seat to population ratio in the most populated province did not exceed 2.75 times that of the least populated one. 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 Aragon expired four years after the date of their previous election. Elections to the Cortes were fixed for the fourth Sunday of May every four years. The previous election was held on 13 June 1999, setting the election date for the Cortes on Sunday, 25 May 2003. The President of the Government had the prerogative to dissolve the Cortes of Aragon and call a snap election, provided that no motion of no confidence was in process, no nationwide election was due and some time requirements were met: namely, that dissolution did not occur either during the first legislative session or within the legislature's last year ahead of its scheduled expiry, nor before one year had elapsed since a previous dissolution under this procedure. 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. Any snap election held as a result of these circumstances would not alter the period to the next ordinary election, with elected deputies merely serving out what remained of their four-year terms.
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. 34 seats were required for an absolute majority in the Cortes of Aragon.
