DC Comics have informed retailers that they are "welcome" to open at midnight on July 4 to sell the milestone Batman #50, along with all other DC items on sale that week.
Based on DC's July 2018 solicitations, that would include Catwoman #1, The Curse of Brimstone #4, Deathstroke #33, Green Arrow #42, Green Lanterns #50, Harley Quinn #45, Injustice 2 #29, Justice League #3, Nightwing #46, Shade the Changing Woman #5, The Unexpected #4, and DC Nation #2.
For the United States, Wednesday July 4 is Independence Day but will be a busy day in comic stores regardless, as Marvel is also launching Captain America #1. Newsarama wrote about this rare Holiday New Comics Day here.
Marvel and other publishers have not announced any plans to allow retailers to begin selling their July 4 titles at midnight.