I love latigo, but:
Sure they can. That is pretty much the definition of malicious prosecution.
A defendant in a civil action CANNOT “counter sue” the plaintiff on the sole grounds that the evidence and applicable law doesn’t support the plaintiff’s claim.
While I like the rest, this is a very unfortunate phraseation. (Is that a word?)
When you are a Bear of Very Little Brain, and you Think of Things, you find sometimes that a Thing which seemed very Thingish inside you is quite different when it gets out into the open and has other people looking at it.
--W. T. Pooh (aka A. A. Milne)