[lotharbot]

> "let's say someone had data which demonstrated that [partisan policy X is] bad.... How could one make that argument in a neutral, non-partisan way"

"It is important to help [group] overcome [disadvantage]. We have new data showing that [policy], while stemming from admirable goals, is ultimately counterproductive, leading to worse outcomes than would be expected without such a policy in place." Then discuss the data, without specifically naming any politician or political party or questioning anyone's motives. Make recommendations based on the idea of doing right by those you're trying to help, rather than making accusations based on the idea of the other side being evil or stupid.

It's certainly true that some people would interpret your statement in a partisan way. Some people would assume you were secretly funded by the Association of Partisan Conspirators. But by focusing on data rather than partisan cheap shots, you would give them little to go on, and you would be more engaging to those who are honestly interested in doing the right thing.