In Winnipeg the law is that a leash can be 20 feet, BUT you have to shorten it to 6 feet when a person or animal is closer than 20 feet.
Flexis are the debbil, IMO. Had a roommate who was taken out on her bike on a path by a doofus owner who let their dog bolt in front of her, and wrap the lead around her front tire. I have a dog that is nervous around other dogs, and more often than not, the owners of dogs on flexis let them charge her, under the guise of "let them meet!" Uh, no thanks.