I have never in my life heard of "leashes" for children. Do you mean the ones for pets used on children? I don't understand - in fact, I'm not even sure I understood correctly, sounds so shocking.
The problem lies in the emotive word "leash", suggesting as it does something like a dog lead, fastened around the neck.
The correct expression is "wrist strap".
- What is it? It's a strap made of e.g. braided nylon, around a metre long with a loop at each end and sometimes an elastic section in the middle.
- How is it used? One end of the strap is looped around the adult's wrist, the other around the child's wrist. The adult holds the child's hand as normal.
- When is its use appropriate? Children like to test limits. It's part of growing up. Especially, around the ages of approx 2-4 yrs children are very impulsive. At the same time they are growing in strength. It's this mismatch between strength and impulsiveness that may make the use of a wrist strap a useful part of a child's upbringing. ("If you promise to hold tightly onto Mummy's hand today, we needn't use the wrist strap today." "Good girl! You've stayed close by me all week. Let's put the wrist strap away.") It can also save a life. Generally it's only needed for a few weeks.
- When is its use inappropriate? When it is used lazily, as a substitute for proper care and attention. When it is used long-term, rather than as a help in difficult circumstances. When it is used cruelly, as a crude means of control, or as a punishment. When it is used for an older child. Note, however, that a special needs child may need some kind of restraint at a greater age, as Heather has pointed out.
I hope everything is clearer now.
EDIT. I'm tempted to lock this thread, and I will do so if the discussion starts to generate even more heat than light. Let's keep it rational, eh? Less of this