Arizona voters have approved letting local police arrest migrants suspected of illegally entering the state from Mexico, an authority that would encroach on the federal government's power over immigration enforcement but would not take effect immediately, if ever. With the approval of Proposition 314, Arizona becomes the latest state to test the limits of what local authorities can do to curb illegal immigration. Within the past year, GOP lawmakers in Texas, Iowa and Oklahoma have passed immigration laws. In each case, federal courts have halted the states' efforts to enforce them. The only presidential battleground state that borders Mexico, Arizona is no stranger to a bitter divide on the politics of immigration. Since the early 2000s, frustration over federal enforcement of Arizona's border with Mexico has inspired a movement to draw local police departments, which had traditionally left border duties to the federal government, into immigration enforcement. The state Legislature