Their success rate is the highest in more than 20 years, according to data released by the Transactional Records Clearinghouse at Syracuse University, which collects and studies federal prosecution records.
The data shows that the U.S. government has been losing more deportation cases each year since 2009.
It does not say how many deportation cases the government successfully appeals.
Immigration supporters accuse the Obama administration of deporting too many people, but Republicans say the president is too lenient on immigrants living in the country illegally. Nearly 2 million immigrants have been removed by U.S. Immigration and Customs Enforcement under President Barack Obama.
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