With XP turned off at level 70, you can get justice points from the first random Wrath dungeon you complete each day (12), from the heroic daily in Shattrath (10), from four Shattered Sun daily quests (5 each), and from bosses in heroic BC dungeons (5 each).
The four Shattered Sun daily quests that award JPs are:
Rediscovering Your Roots (available in Quel'Danas from Mar'nah, takes place in Terokkar)
Sunfury Attack Plans (available from Lord Torvos in Shattrath, takes place in Netherstorm)
Blast the Gateway (available from Magistrix Seyla at the Throne of Kil'jaeden, takes place there)
Maintaining the Sunwell Portal (available from Exarch Nasuun in Shattrath, takes place in Blades Edge Mountains)
For the BC heroics, your entire party must be comprised of level 70 characters. If even one player is level 71 or higher, you will not get JPs for that boss.