A state appeals court on Monday upheld New Jersey’s use of electronic voting machines, but the judges expressed serious concerns about possible human error and ordered further review of the state’s safeguards. Monday’s ruling, which upheld a lower court decision, is the latest in a legal battle dating back to 2004 when state Assemblyman Reed Gusciora and others sued over the state’s use of the machines. The lawsuit claimed the touch-screen systems, called direct recording electronic voting machines, were unreliable because they didn’t produce a paper backup and were susceptible to hacking. Then-Gov. Jon Corzine signed legislation in 2005 that would have required all machines to be retrofitted with a paper backup system by January 2008, but that deadline wasn’t met and in 2009 lawmakers suspended it indefinitely over a lack of funding.