Consider the DOJ's own report, "A Policymaker's Guide to Hate Crimes." [pdf] Even if the numbers, nationally, appear to follow any sort of trend since the inception of hate crime enhancements, any potential causality is likely ruled out by intervening variables--population growth, other anti-crime legislation, differences in enforcement, and differences in data gathering. The latter is even more complicated:
...even if all States were reporting these incidents it would be difficult to gauge the level of the hate crime problem in this country because bias-motivated crimes typically are underreported by both law enforcement agencies and victims.I'm still searching, though. If you find quality research done in the past couple years that shows a clear effect, send it along. Otherwise, unless you have good data, stay away from the deterrence argument on the Neg for the current resolution.