Connecticut is suing federal immigration enforcement over the refusal to honor the state's pardon system when it comes to immigration.
In a lawsuit filed Thursday, Attorney General William Tong argued officials have abandoned decades of practice and singled out the state for "deeply unequal" treatment by refusing to recognize state pardons.
Federal immigration officials contend a pardon needs to come from the governor or the president under a waiver program.
In Connecticut, pardon board members are appointed by the governor.
In July, Tong argued that federal immigration authorities have started the process to deport some state residents with past criminal records even though their crimes were pardoned by the state's Board of Pardons and Paroles.
Five other states have similar systems, including Alabama, Georgia, Idaho, South Carolina and Utah.