If you've got multiple cats, you know it's not unusual for them to get into tiffs every so often. And, let's be honest, sometimes these cat fights get pretty nasty. But submissive urination isn't typical. If one of your cats is peeing in inappropriate places, you'd best address the problem.
Ferret Out the Issue
Assuming you clean their litter boxes regularly, cats are pretty consistent about where they go to the bathroom. (Their natural instincts are to bury their waste to throw potential predators off their trails.) If your cat's urinating somewhere he shouldn't be, try to figure out what's bothering him. Dirty boxes can lead him astray, so could health issues. In rare cases, incontinence might be the issue. Cats are much less likely to submissively urinate than dogs, but that doesn't mean it never happens. It's almost always in multi-cat homes. Watch how your cats interact -- you'll have to catch them in the act to make sure you're dealing with submissive urination issues. See a veterinarian if it's not obvious you're dealing with submissive urination.
It's not hard to spot a submissive cat. They avoid eye contact; their ears face backward; they crouch low to the ground; they tuck their tail between their legs; occasionally, they lie on their back with their belly up. These behaviors usually cluster. Odds are, you'll spot your cat looking like this right before he urinates somewhere he shouldn't. Nearby, you'll likely see the other offending party. See how his whiskers are spread out, his eyes are narrowed and his ears are up and turned straight backward; maybe he's baring his teeth or growling -- that's the aggressor. He's probably standing sideways, and his tail is lashing about.
Aggresion and Submission
If your cats constantly fight, you've got the potential for submissive cat urination. As one of the two (or three... or however many) assert dominance over another, the low kitty on the totem becomes meeker, more defensive. The aggressor may continue harassing the submissive cat, even when he's in the litter box. This is what leads to submissive urination. Once a cat feels threatened and doesn't feel comfortable using the litter box, he either urinates out of necessity, or when cornered, out of fear.
Approaches and Considerations
Breaking up cat fights isn't a practical way to stop submissive cat urination. You need to create an environment where the submissive cat can use the litter box in peace. This may require additional litter boxes, maybe in out-of-the-way nooks. You can try stress-reducing cat sprays, although few, if any, have science to back up their claims. Feeding your cats together and playing with them at the same time can ease some tensions, but it's rarely a quick fix. In extreme situations, you may have to confine your cats to separate living areas. Even then, a cat who submissively urinates may take time to start using the litter box again. Be patient. Consult a vet or animal behaviorist if problems persist.