Avvo Corp. of Seattle, an Internet-based startup that “rates and profiles every lawyer so you can choose the right lawyer,” is facing a class action brought by those rankled by the rankings.

The company, which ranks lawyers on a scale of one to 10, with the three lowest categories being “extreme caution,” “strong caution” and “caution,” has made for lively chatter in the legal blogosphere since it debuted last week — and has upset lawyers slighted by its ratings.