In the UK it is illegal for a dog to poo in your garden, but not a cat.

(That said, public fouling is only an offence when it is not immediately cleaned up. UK dog owners who fail to scoop their dog’s poop can be slapped with a £1,000 fine under the Clean Neighbourhoods and Environment Act 2005.  But cats can pretty much do what they want, when they want; hence their expression of superiority.)