The 77-year-old's tough stance on immigration and controversial tactics, which include using traffic violations as a means to check the vehicles for anyone he thinks may be an illegal immigrant, has helped him win five consecutive terms as sheriff and catapulted him into the national spotlight.
Since he began his efforts in 2005, Arpaio claims he's arrested around 30,000 illegal immigrants. But America's ultimate law enforcer hasn't been without his share of controversy. Protesters frequently gather outside Arpaio's office.
The Department of Justice has launched an investigation into his methods. And his wings were recently clipped after the government removed his deputies' right to enforce immigration laws on the streets, amidst allegations that he was racially profiling Hispanics. A federal program called 287(g) had enabled Arpaio to enforce immigration law in his county.
Even after his powers were relegated, last month Arpaio announced his 13th illegal immigrant crackdown of the year.
"Nightline" joined Arpaio and Deputy Cory Rengel in their latest highway pursuit.
"We reward people for illegally coming into this country and committing a crime by coming into this country, reward them with jobs," Arpaio said. "I'm not getting into the social aspect, but you do know if you go into the ER many people here [entered] illegally where U.S. citizens have to wait in the back of the line and they get angry about this."
Arpaio says that illegal immigrants are not only criminals, but can bring diseases into the country.
"I have a problem with people crossing this border that have not been checked medically," he said. "I'm very concerned."
Arpaio demurred when asked which ailments illegal immigrants bring into the country, but said, "I don't know -- TB is a big one. We have people in our jail that have TB. Nobody checks them."
The government investigation into his tactics has ticked off Arpaio.
"They do not like me stopping illegal immigrants on the streets, enforcing the laws, they don't like that. They don't like it because stopping people on the streets because they look Hispanic is racial profiling? That's what they say, but we don't do that," he said. "We use minor misdemeanors to catch dope dealers, seize drugs, catch DUIs."
When asked if he considered an illegal immigrant as serious a criminal as a rapist and a murderer, Arpaio demurred.
"Well, I don't know," he said. "I'm not going to compare the type of crime."
And what about criminals like pedophiles? Arpaio said his office is "very serious" about pedophiles, putting many resources towards a county crackdown on pedophilia.
When "Nightline" asked why his office doesn't take aggressive action against pedophiles as it does against illegal immigrants, Arpaio said, "we're clamping down on murders, but nobody will print it, they'll laugh at me."
"[Illegal immigrants,] that's a high interest of this country right now," he added. "And this county and putting resources towards that. I have $1.6 million from the state [legislature] just to do that, not to go after murders, just to go after this specific crime."