The Justice League is DC Comics Famous team of all their best Super Heroes. All include, Superman, Batman, Wonder Woman, The Flash, Green Lanterns (Both Hall Jordan and John Stewart are on the team) Martian ManHunter, Aquaman, Shazam and several others.
While neither hero has appeared in ppgd, It has been establish they do exist in that continuity. Which would mean they also exist with the Justice Friends.
It would be safe to assume that this particular Justice league is the one of WB/ Bruce Timm's Famous DCAU