A riddle

The dogs on my street have convened a conference and seem to be debating something important. So I've pretty much kissed my sleep good bye. Which isnt too bad.

Given the excess time on hand, I started mulling over a couple of tricky spots I've been in. I'll drum up an analogy.

Lets say you see me walking on the road, and there's a tree ahead of me in full sight. You call out to me, and right then I bump into the tree. Who's fault is it? Mine, yours, or the tree's ?
Ah. Hold that thought. I haven't told you that I bumped into the tree because I slipped on a banana peel. So who's fault is it now ?