August 2003 (updated August 2006)
Most elected bodies in American government are elected according to winner-take-all rules (some by plurality, some by majority). The largest exception is Puerto Rico, an American territory with 3.8 million American citizens. Puerto Rico uses an unusual form of proportional representation to elect members of its Legislative Assembly, that likely contributes to generating one of the highest levels of voter participation in the western hemisphere -- and higher than any of the 50 states in the 2000 presidential election.
The Legislative Assembly of Puerto Rico has two chambers, the Camara de Representantes (House of Representatives), and the Senado (Senate).
The House has 51+ members, and the Senate has 27 + members. The + refers to the fact that the size of the legislature can fluctuate slightly based on the results in a given election, due to the Law of Minorites, which is explained below.
Of the 51+ House members, 40 are elected in single-member districts using plurality voting. 11 are elected at large using the "one vote" version of limited voting, or the Single Non-Transferable Vote (SNTV) system.
Of the 27+ Senate members, 16 are elected in two-member districts using a winner-take-all, at-large system (at-large plurality, or block vote). 11 are elected at large using SNTV.
As of August 2003, three parties have seats in the Legislative Assembly. These are the PPD (Popular Democratic Party), the PNP (New Progressive Party), and the PIP (Puerto Rican Independence Party).
Technically, parties can nominate up to 11 candidates
for the SNTV seats in the House, and 11 for the SNTV seats in the
Senate. This limit helps ensure more proportional results by making it
more difficult for a party's' nominees to "spoil" each other's
candidacies. In practice, though, PPD and PNP tend to nominate 6
candidates for each chamber, and the PIP usually only nominates one.
Also, the larger parties vary the order of their candidates on the
ballot from area to area, so that each candidate is on the top of the
list on a roughly equal number of ballots. Voters usually select the
top choice for their party on the ballot they receive, which means that
most candidates running from the same party usually receive a roughly
equal number of votes for the SNTV seats in each chamber. This practice
also helps ensure more proportional results by minimizing wasted votes.
Unlike choice voting, the one vote system does not shift otherwise
wasted votes to next-ranked candidates.
It remains possible for parties to lose seats by
running too many candidates ("spoiling" each other by splitting the same bases of support)
or too few candidates (hence not contesting many seats as they
could actually win).
Law of Minorities
Additional members can be added to the Senate or to the House of Representatives, according to the provisions of the Law of Minorities.
This law states that if any party has more than two thirds of the seats in either chamber, but has not received two thirds of the vote for the office of Governor, then the opposition parties are eligible for additional seats, in order to give the opposition (collectively) one third of the seats in the chamber .
So, if a majority party did not receive over two thirds in the gubernatorial election, then the opposition (collectively) is entitled to 9 seats of the 27+ seats in the Senate, and 17 seats of the 51+ in the house.
Parties must have at least 3% of the vote for governor in order to qualify for additional seats.
The additional seats are divided up among minority parties in proportion to their shares of the vote for Governor. That is, they are added such as to bring a minority party's share of the opposition seats closer to their share of the opposition votes for Governor.
In the 2000 election, one seat was added to the Senate (which the PNP received), in accordance with the law of minorities, because the PDP had just over two thirds of the seats. No seats were added to the House of Representatives, because no party had over two thirds of the seats there.
The law of minorities is unlikely to add
more than a handful of seats to the Assembly. It has come into
effect in 1952, 1956, 1960, 1964, 1972, 1988, 1992, 1996 and 2000.
Turnout
2,022,276 people voted in the 2000 elections, which is 82.6% of enrolled voters, and 74.4% of the over-18 population (which was 2,716,509 according to the US Census).Overall Proportionality
Although the SNTV seats and the
law of minorities do offer some help, the overall results of Puerto
Rican elections, determined mostly by the district elections, tend
to be highly disproportional.
This table shows the results of the election for Puerto Rico's Legislative Assembly, which took place on November 7, 2000. It also calculates differences between the percentage of votes and the percentage of seats that the parties received.
For example, the PPD (Popular Democratic Party) received only 46.5% of the total votes for Senate, but they received 67.9% of the actual Senate seats, while the PNP (New Progressive Party) received 45.3% of the votes and only received 28.6% of the seats.
This effect is known as disproportionality, and of course it is considered to be unfair to parties who receive a much smaller share of the seats than their share of the vote. Proportional representation systems nearly always have less disproportionality than winner take all systems.
For example, the single non-transferable vote (SNTV) system used to elect 11 members of each house is considered to be a proportional representation system, at least to a large extent.
This data clearly shows that the disproportionality is much greater in the plurality part of the election than the SNTV part. The percentage of SNTV votes and the percentage of SNTV seats won by each party are always within 3% of each other, whereas the difference between votes and seats won in the plurality elections is much greater, ranging from 5.8% to 39.4%.
See the bold numbers in the next two tables. % district seats - % district votes indicicates the disproportionality of the district vote. % SNTV seats - % SNTV votes indicates the dispropotionality of the SNTV vote (which is always substantially lower in these elections). Higher numbers in these rows indicate greater disproportionality.
| Party | PNP | PPD | PIP | Total |
| District Votes Senate | 1,778,197 | 1,850,091 | 221,411 | 3,849,699 |
| % District Votes Senate | 46.2% | 48.1% | 5.8% | 100.0% |
| District Seats Senate | 2 | 14 | 0 | 16 |
| % District Seats Senate | 12.5% | 87.5% | 0.0% | 100.0% |
| % district Seats - % district votes, Senate | -33.7% | 39.4% | -5.8% | 0.0% |
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| Party | PNP | PPD | PIP | Total |
| District Votes HOR | 902,708 | 934,611 | 112,592 | 1,949,911 |
| % District Votes HOR | 46.3% | 47.9% | 5.8% | 100.0% |
| District Seats HOR | 15 | 25 | 0 | 40 |
| % District Seats HOR | 37.5% | 62.5% | 0.0% | 100.0% |
| % district Seats - % district votes, HOR | -8.8% | 14.6% | -5.8% | 0.0% |
| Party | PNP | PPD | PIP | Total |
| SNTV Votes Senate | 856,886 | 855,013 | 217,390 | 1,929,289 |
| % SNTV Votes Senate | 44.4% | 44.3% | 11.3% | 100.0% |
| SNTV Seats Senate | 5 | 5 | 1 | 11 |
| % SNTV Seats Senate | 45.5% | 45.5% | 9.1% | 100.0% |
| % SNTV Seats - % SNTV votes, Senate | 1.0% | 1.1% | -2.2% | 0.0% |
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| Party | PNP | PPD | PIP | Total |
| SNTV Votes HOR | 851,506 | 857,614 | 224,765 | 1,933,885 |
| % SNTV Votes HOR | 44.0% | 44.3% | 11.6% | 100.0% |
| SNTV Seats HOR | 5 | 5 | 1 | 11 |
| % SNTV Seats HOR | 45.5% | 45.5% | 9.1% | 100.0% |
| % SNTV Seats - % SNTV votes, HOR | 1.4% |