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Scorporo (Italian:[ˈskɔrporo],lit. 'parceling out') is apartially compensatory,mixed-member majoritarianelectoral system, sometimes referred to as anegative vote transfer system^[1] (NVT) whereby a portion of members are elected insingle-member districts (SMDs) and a portion are elected from alist. It may be fully defined as aparallel voting system which excludes a portion (up to 100%) of the SMD winners' votes in electing the proportional tier, to result in a moreproportional outcome. The exclusion of a portion of the SMD winners' votes is what makes scorporo fundamentally different fromparallel voting and somewhat closer to theadditional member system in the UK (a form ofmixed-member proportional representation) in theory. However, the design proved particularly susceptible to thedecoy list strategy, and as a result by 2001 had devolved into ade facto parallel voting system. The scorporo method is only known to have been used in Italy, but a similar version is in used for theNational Assembly of Hungary.

Scorporo was in force for elections to the bicameralParliament of Italy based on Law 277/1993 from 1993 to 2005. Under this system, members could be elected in two ways:

• 75% of elected members were elected in single member districts (SMDs) usingfirst-past-the-post voting.
• 25% of elected members were elected on list basis based on the proportion of the votes received by the party (using theD'Hondt method), with the exclusion of a proportion of any first-placed winner's votes.

The system was subject to the following specific rules for each chamber:

• List seats were calculated at the regional level.
• All votes for winning candidates were excluded from the list allocation.
• No threshold was applied for list seats.
• The SMD vote and the list vote were linked (mixed single vote) limiting the use of decoy lists (see below).

• The list seats were calculated at the national level.
• The number of SMD winner's votes excluded from the list vote was equal to the second place candidate's vote total, representing the number of votes needed to elect the winner in the SMD (i.e. non-wasted votes).
• A 4% threshold was established for parties to qualify for the list seats.
• The local vote and list vote were not tied to each other, thereby providing an incentive fordecoy lists (see below).

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It has been suggested that this section besplit out into another article titledDecoy list. (Discuss)(June 2024)

Symbols of the twoliste civette

In the2001 Italian general election, one of the two main coalitions (theHouse of Freedoms, which opposed the scorporo system), linked many of their constituency candidates to adecoy list (lista civetta) for the proportional component, under the nameAbolizione Scorporo (Abolish Scorporo). This list was not designed to win proportional seats, but only to soak up constituency votes for House of Freedoms, enabling them to win a larger share of the proportional list seats than they would be entitled to if all candidates were linked other House of Freedoms parties. This intentionally undermined the compensatory nature of the electoral system. As a defensive move, the other coalition,The Olive Tree, created their own decoy list under the namePaese Nuovo (New Country).

The decoy lists were extremely successful. Between them, candidates linked to the decoy lists won 360 of the 475 constituency seats, more than half of the total of 630 seats in the Chamber of Deputies. Meanwhile, the decoy lists won a combined total of less than 0.2% of the proportional part of the vote. For the two main coalitions, their vote totals in the proportional component were essentially unaffected by the constituency votes, enabling them to win far more proportional seats than the system was designed for. In the case ofForza Italia (a party within House of Freedoms), the tactic was so successful that it did not have enough candidates in the proportional component, and its list exhausted before it could be awarded all the seats it had won, ultimately missing out on 12 additional seats.

This was facilitated by the fact that this particular scorporo system allowed the single-member constituency vote and the proportional list vote not to be linked. Decoy lists are a common issue in all compensatory and pseudo-compensatory systems, and this was not a unique problem for scorporo.

Due toSilvio Berlusconi's opposition to the system, Italy changed to amajority bonus system in 2005.^{[citation needed]}

In2018,parallel voting was brought back by theRosatellum law.^[2]

• Elections in Italy
• Additional member system

• Semi-proportional electoral systems
• Elections in Italy
• Mixed electoral systems

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