Directories using company url to rank higher - legal?

Several web directories are using our URL's to rank higher in Yahoo search

[nheerdt]

We have noticed that a number of directories are now using our exact URL as a way to rank higher in yahoo. Meaning, when you type in one of our cononical URL's into yahoo, it brings back several listings that say our URL in the name/title but link back to a directory page on their site. This page has a link to our site along with several other of our competitors.

My question to whoever can help me with this are:

1. Can they do this legally?
2. If not, how do you go about stopping this - through the directory or through Yahoo?
3. If through the directories, does anyone have any previous examples of this and the end result?

I would really appreciate some help on this. I apologize if this has been discussed before. I did search but could not find a string on it. Thanks very much!