In an interview with Newsarama, the scribe also explained that the landmark comic will mark a tonal shift for the series.
"You see that tonal shift in a big way with the 50th issue. There are a lot of inspirational moments," he said. "George Pérez has drawn a beautiful ten-page story that provides a new perspective for how the Justice Society fits into the larger DC Universe.
"You've got the return of Per Degaton, which harkens back to an earlier era of the Justice Society. You have Jay Garrick getting sworn in as the mayor of Monument Point. As a result of that, there is a tonal shift back to a less dark version of the Justice Society."
The writer went on to reveal that characters from the recently cancelled JSA All-Stars series will be incorporated into the Justice Society. "Now that the cat's out of the bag, I can officially say that, with the exception of Power Girl, all the JSA All-Stars will move over to Justice Society," he added.
Guggenheim is best known for his work on Marvel's Amazing Spider-Man, which concluded in 2009. He took the reins on JSA last summer.
Justice Society Of America #50 arrives in stores next month.