From The Wall Street Journal:

At least with respect to immigration enforcement, Homeland Security is an agency that has lost sight of its own policies. The result is that several hundred thousand of the immigrants passing through state or county jails each year are then flagged on DHS orders—often in violation of the department’s own policies meant to separate ordinary people from dangerous criminals and terrorists—and end up being deported…Since 2003, the department’s Immigration and Customs Enforcement agency has turned into a deportation machine, spending a budget of $18 billion that exceeds the budgets of all the rest of federal law enforcement combined.