concurring in part and dissenting in part:
The majority approves the reapportionment plan as adopted by the Colorado Reapportionment Commission (Commission) over certain objections which were raised as to the new boundaries of senate districts 32 and 35. Because it is unfortunately clear from the record that incumbency considerations alone controlled the Commission’s final decisionmaking as to the redistricting of these two senate districts in contravention of the constitution, I respectfully dissent. When, as here, the Commission rejects a plan solely because of incumbency considerations and approves an amended plan which is not demonstrably superior to the original plan under any of the constitutional criteria, then this court must reject the final plan.
Although this court’s role in the reapportionment process has been described as “narrow,” In re Reapportionment of Colo. Gen. Assembly, 647 P.2d 191, 194 (Colo.1982) (Reapportionment I), it is a role of fundamental importance and must be performed carefully in light of the purpose and intent of the reapportionment section of our constitution. Colo. Const. Art. V, § 48. The constitutional amendment establishing the Commission was an initiated amendment adopted by the People of Colorado in 1974. By this amendment, the People removed the power and responsibility for legislative reapportionment from the General Assembly and placed it in a separate body which is to function as a nonpartisan Commission. The intent of the amendment was to:
clarify the present constitutional requirement for compact districts by providing that the “... aggregate linear distance of all district boundaries shall be as short as possible.” The intent of the [amendment is] to avoid irregularities in district boundary lines which may be placed in a reapportionment plan for reasons not related to natural boundaries, population requirements, and census and local government boundaries.
Legislative Council of the General Assembly, An Analysis of the 1974 Ballot Proposals, Research Publication No. 206 (1974), at p. 28.1 The constitutional criteria include substantial equality of population among the senate and house districts, Colo. Const. Art. V, § 46; no unwarranted division of counties, Colo. Const. Art. V, § 47(2); as much compactness as possible, *211Colo.Const. Art. Y, § 47(1); and wherever possible the preservation of communities of interest, Colo. Const. Art. V, § 47(3). In re Reapportionment of Colo. Gen. Assembly, 647 P.2d 209, 210-11 (Colo.1982) (.Reapportionment II).2 Although substantial equality of population is the “paramount criterion for testing the constitutional sufficiency of a reapportionment plan,” Reapportionment I at 193, that criterion alone does not prevent gerrymandering. Hence, the constitution provides the additional neutral criteria designed to minimize gerrymandering. Davis v. Bandemer, 478 U.S. 109, 168 n. 5, 106 S.Ct. 2797, 2802 n. 5, 92 L.Ed.2d 85 (1986) (Powell, J., concurring in part and dissenting in part) (“Advances in computer technology achieved since the [‘one person, one vote’] doctrine was announced have drastically reduced its deterrent value by permitting political cartographers to draw districts of equal population that intentionally discriminate against cognizable groups of voters. For ‘one person, one vote’ to serve its intended purpose of implementing the constitutional mandate of fair and effective representation, therefore, consideration also must be given to other neutral factors.”) (citation omitted).
With the exception of preserving communities of interest, the law existing before the 1974 amendment required the General Assembly to reapportion the districts according to much the same neutral criteria. Thus, the major change introduced by the amendment was the establishment of the Commission which is to be, in the Commission’s words, “a politically neutral body.” See Commission, Response to Objections to Final Plan, at 1. By vesting reapportionment power in the Commission, the amendment intended:
to reduce the impact that partisan politics can have on the drawing of legislative district boundaries, through the placement of the commission outside the legislative branch and through the requirements for appointment of commission members by all three branches of state government. The [amendment’s] more stringent requirements for consideration of communities of interest, for compact districts, and for minimization of the splitting of cities and towns, and the public visibility of the activities of the reapportionment commission would tend to reduce the gerrymandering of legislative districts.
1974 Ballot Analysis, at 29-30. Plainly, then, discontent with the General Assembly’s reapportionment track record, which was prone “to endless battles over redistricting and to enmity among state lawmakers,” id. at 30, was the major motivation which led to the adoption of the amendment. In sum, by re-affirming and clarifying the criteria for redrawing the districts and by creating the Reapportionment Commission itself, the amendment minimized considerations of incumbency from the decision-making process of reapportionment.3 If, as we said in Reapportionment I at 194, communities of interest is the least weighty of the reapportionment criteria, incumbency ranks even lower. It has no acknowledged status as a criterion under the amendment and, indeed, is one of the perceived evils which caused the voters to remove reapportionment from the hands of the incumbent legislators.
According to the Commission, the Denver senatorial districts posed certain problems. Because of population shifts, Denver was slated to lose one senate district, dropping from six districts to five. After the Commission drew three “minority” districts (senate districts 31, 33, and 34), the Commission then “divided the rest of Denver” into two districts, senate districts 32 and 35. Commission, Legal Memorandum and Explanatory Materials in Support of Final Plan, at 29.
The original plan for senate districts 32 and 35, computed on January 11, 1992, and *212approved by the Commission before noon on January 13, 1992 (1-11 plan), divided the rest of Denver so that three Denver incumbents were placed in one district, namely district 32, with district 35 embracing no incumbent. The vote for the 1-11 plan was eight votes in favor to three opposed. On the same day, after lunch, the Commission reconsidered and voted six to five to redraw the rest of Denver, this time placing two democratic incumbents in one district and a republican incumbent in the other district. The Summary of Meeting of the Commission meeting for January 13, 1992 states:
11:47 [a.m.] — Denver Senate Districts
Mr. Monaghan made a motion to adopt the 1-11 Senate plan as the commission’s final plan, with the exception of Pueblo County. Sen. Wells made a substitute motion to adopt the WELLS/VI plan for Denver. The substitute motion failed on a 5-6 roll call vote.
Mr. Monaghan renewed his motion to adopt the 1-11 senate plan as the commission’s final plan. The motion passed on a 8-3 roll call vote.
12:00 [noon]
The meeting was recessed.
12:50 [p.m.] — [meeting reconvened]
* * * 4c * *
1:13 [p.m.] ...
Mr. Ritchie, having voted on the prevailing side, made a motion to reconsider Denver Senate districts and adopt the WELLS/VI plan. Mr. Monaghan made a substitute motion to adopt the 12-19 plan as the final plan. The substitute motion failed on a 5-6 roll call vote. The original motion carried on a 6-5 roll call vote.
As indicated by the summary, the post-luncheon division of the rest of Denver, known as the Wells plan, was incorporated in the final plan. News reports summarized the Commission’s action as follows:
One last-minute adjustment yesterday changed an earlier commission decision to put two incumbent senators, Republi-cia. Dottie Wham and Democrat Pat Pas-coe, in the same Denver district.
Instead, Pascoe wound up in the same Senate district with Democrat Ray Peterson, who is halfway into a four-year term. Pascoe loses that face-off, because her current term ends in 11 months.
Denver Post, January 14, 1992, at p. 3B.
In a Senate district dispute, the commission voted narrowly to place Sen. Dot-tie Wham in her own south Denver district and put two Denver Democrats together in another — Sens. Pat Pascoe and Ray Peterson. Peterson, who has three years to go in his term, will automatically keep his seat next year because Pas-coe’s term has expired.
Rocky Mountain News, January 14, 1992, at p. 16. The vice-chair of the Commission, Gene R. Nichol, dissented from the Commission’s final plan as to the senate districts because he concluded that “ ‘a constitutional standard the Commission is required to obey — compactness—was sacrificed for political concerns not within our charge.’ ” Denver Post, February 8, 1992 at p. 7B. The political concern was the “ ‘desire to protect the incumbent.’ ” Rocky Mountain News, Jan. 14, 1992, at p. 16.
The influence of incumbency is the only reason apparent on the record for the change in the boundaries of senate districts 32 and 35. No supportive evidence to the contrary was presented by the Commission in its briefs. There is no evidence showing how the last-minute Wells amendment to the final plan enhanced any of the specific reapportionment criteria provided in the constitution.4
The Commission argues that the final plan for senate districts 32 and 35 is at least as compact as the rejected 1-11 plan. Compactness is one of the constitutional criteria which each district must meet as much as possible. Colo. Const. Art. V, § 47. The Commission used two computational tests, the so-called Reock and *213Schwarzberg tests, to derive a mathematical measure of compactness. Although each test has been criticized, the gist of each test is that the closer the derived measure approaches the value of 1.0 the more compact the area measured. As redistricting proceeded and different boundaries were considered, the Commission computed the numerical values of compactness for the various proposed districts under both tests.
The last-minute Wells amendment to the final plan did not improve the compactness of the two senate districts by which the Commission divided the rest of Denver. The numerical values of compactness derived for senate districts 32 and 35 under the different plans are not disputed. Under the 1-11 plan, the Reock and Schwarz-berg values for senate district 32 are 0.1990 and 3.2909, respectively. Under the final plan as amended, the Reock and Schwarzberg values for senate district 32 are 0.1951 and 3.2673, respectively. Thus, under the 1-11 plan, senate district 32 is more compact according to the Reock test but less compact according to the Schwarz-berg test.
Under the 1-11 plan, the Reock and Schwarzberg values for senate district 35 were 0.4708 and 2.3110, respectively. The final plan’s Reock and Schwarzberg values for senate district 35 are 0.4803 and 2.4324, respectively. Thus, under the 1-11 plan, senate district 35 is less compact according to the Reock test but more compact according to the Schwarzberg test.
The Commission states that this contrast and comparison of the test values of compactness between the different plans yields inconclusive results and that therefore the Commission is entitled to a presumption in favor of the final plan. However, no such presumption attaches when the Commission adopts a certain plan which satisfies the constitutional criterion of compactness and then rejects that plan in order to protect incumbency. This is especially true when the Commission cannot demonstrate that the eleventh-hour change improves the final plan by increasing compactness or compliance with any other constitutional criteria.5
Thus, in my view, when districts are redrawn after holding the public hearings which are required under § 48 and such changes are not supported by any evidence that a constitutional criterion was more closely adhered to or met, the final plan is not entitled to deference but should be subjected to a more exacting level of review by this court. Direct evidence of the determinative influence of incumbency (influence which the Commission admits in this case) requires this court to disapprove the offending amendment and to reinstate the original boundaries which were fully supported by evidence of adherence to constitutional criteria. By lending its approval to senate districts 32 and 35 as submitted by the Commission, this court endorses a plan which was designed solely for the protection of incumbency. The voters refused to allow reapportionment decisions to be controlled by incumbency considerations and so should we.
Accordingly, I dissent.
QUINN, J., joins in this concurrence and dissent.
. See Carrara Place v. Bd. of Equalization, 761 P.2d 197, 203 (Colo.1988) ("The legislative council's interpretation, while not binding, provides important insight into the electorate's understanding of the amendment when it was passed.").
. In addition to these criteria, redistricting must also meet the requirements of the federal constitution and the federal Voting Rights Act of 1965, as amended in 1982, 42 U.S.C. § 1973 (1988).
. See Bernard Grofman, "Criteria for District-ing: A Social Science Perspective,” 33 UCLA L.Rev. 77, 151 (1985) (describing "incumbent-centered partisan bias” as the antithesis of redistricting based on neutral factors and as "a prime tool of political gerrymandering.”).
. See Art. V, § 48(l)(e), which provides that the "supreme court shall adopt rules for [its review] proceedings and for the production and presentation of supportive evidence for such [final] plan." (Emphasis added.)
. Although the absolute values of the differences in the two tests may be incommensurable, the final plan’s net gain over the 1-11 plan in Reock compactness between districts 32 and 35 is 0.0056, which is less than the final plan’s net loss from the 1-11 plan in Schwarzberg compactness between districts 32 and 35, which is 0.0878.