A Pennsylvania Commonwealth Court judge has ruled that some voters are entitled to a trial over the reliability of vote-counting machines used in Philadelphia and Northampton Counties. See this story. The machines, known as ExpressVote XL, are manufactured by Elections Software & Systems (ESS) Corporation. They work by having a voter insert a blank ballot into the machine. Then the voter uses the computer touch-screen to mark the ballot.
Most vote-counting machines in the U.S. are different. They ask the voter to fill out a paper ballot, which is then inserted into the vote-counting device.