My boyfriend and I had an incident the other day with a woman and her son (approx 3 yrs/old) who she had on a leash. But she had him on more then just a leash, she had him tied to a table. Long story short, neither I nor my boyfriend think putting your child on a leash is right, and them up takes the whole leash idea to a whole 'nother level.
My personal opinion is, if you can't discipline your child to behave (without a leash) then you shouldn't have children. They aren't a pet to put on a leash and/or tie up.
But that's MY opinion.
Open for DEBATE only :)
P.S. The ONLY thing I would consider a good reason to have a leash on your child for is if your a grandparent who is too old to keep up with a youngster but you want to take your grandchildren out to the mall or something.