Hobbles are regularly used on working/droving horses, when camping in the open (esp before the days of easy electric fences :P ) to ensure(well, make it likely) the horses would still be close by in the morning, but they can still wander & graze.
These type of hobbles are different to those used for breeding or pacing racehorses. Those types join the back legs to the front, to prevent cantering or kicking. The types used for camping are like handcuffs, going around the front lower legs.
The horse can walk with small steps so they can graze, but the purpose is to prevent them from trotting or cantering. Trotting is impossible with them, but if you're unlucky(or stupid), the horse can learn how to canter with them.
I say stupid, because I've actually seen someone preparing for an epic trail ride, teaching her horses to canter in hobbles... her reason was that they would only do it in an emergency(tho there're no horse eating predators in Oz). Surprise surprise, the second morning of her trip, the horses decided they didn't want any more work & ran away! She resorted to tethering & having to feed hay the rest of her trip, when she finally recovered them! :roll:
If you're thinking of using them, make sure you supervise in an area where the ground's soft enough, for the first few sessions, because horses will often fall on their knees a few times before learning how to cope with them.