I have written on several occasions about how the data demonstrate pretty conclusively that immigrants are not driving a crime wave in Arizona (here and here). The one exception to this may be well-armed quasi militaristic gangs raiding near the border. These guys are certainly running rampant in Norther Mexico and conflicting reports have them making certain US border regions nearly unlivable.
OK, but how is this crime a justification for state laws that harass day laborers and companies that hire immigrants, while requiring law enforcement to check immigration status at traffic stops? One could technically describe the German army in 1941 as illegal immigrants in France, but I don't think this euphemism would trick anyone into thinking that Arizona-style immigration laws would have saved France from Guderion, Rommel and company.
There is zero in SB1070 that will do one little thing to phase such gangs. So how can people with a straight face use such crime as justification for the bill?