"Brown weed" ...Weed killer

[TrueGard]

Dear Fellow Garders,

I have very serious "brown weed" problem, it smells extremely bad and is very unpleasent to the eye!!
also I have grand children running around and playing in the garden and I am frankly very concearned.
as all attempts of finding a resolution have failed and even hightening the fence has not bettered the situation,

I would like to ask if anyone here has experience in this respect.
Can I kill my neighbours dog with weedex if he is on my land?
do you know what the legal implementyations in such a scenario are?

Looking forward to all contributions,

Sincerely,

TrueGardener.