If desired, wipe rims of eight 16-ounce beer glasses or mugs with a lemon slice; dip rims in finely chopped crystallized ginger.
In a large pitcher, combine the 3 tablespoons crystallized ginger and the lemon juice; muddle with a wooden spoon. Pour in beer and ginger ale; stir gently to combine. Serve in the chilled glasses or mugs. Garnish with lemon slices.