The comedian John Oliver lampooned President Donald Trump’s plan to spend $314 million to recruit, hire, and train 500 new Border Patrol agents and 1,000 new Immigration and Customs Enforcement officers in 2018.

“These new personnel would improve the integrity of the immigration system by

adding capacity” to stop people from entering the United States illegally, and to remove those who have already entered, Trump’s budget proposal says.

Adding capacity quickly hasn’t always worked well, however.

Oliver’s segment focused on how difficult the job of a border patrol agent can be, given its mixture of humanitarian work and law enforcement. Border Patrol agents are responsible for engaging with a population of people that spans “the Venn diagram of hardened drug dealers and people who need blankets,” Oliver said. That’s why a hiring blitz like the one Trump is suggesting raises concerns about corruption, he argued.

As my colleague Jeremy Raff reported in May, Customs and Border Protection traces much of its corruption problem to a post-9/11 hiring surge, when the agency doubled its ranks from 9,821 agents in 2001 to 20,119 in 2009. “In order to inflate its force that quickly, CBP relaxed its hiring standards,” Raff wrote. “Border Patrol sent some agents into the field before background checks were complete, and unlike other federal law-enforcement agencies, they didn’t use polygraphs to vet applicants.”