I have an idea that you might consider. While there are different ways to make introductions, and i'm sure you have already tried LinkedIN and other lead generation programs that can help you by targeting companies? But if you are targeting law firms, often law firms need to bring in presenters for continuing education. If you have something to offer that could be considered for education, you might use this as a way to make a connection with the law firms - once they know you, they may be more open to partnering with you in order to introduce you.
-JL