My last law firm was one of the largest. I was not aware of hiring of any undergrads as interns. We would hire law students during the summers as "summer associates" and then make a permanent offer those who worked out as an associate after law school graduation. Interns typically don't get paid. I just checked out current summer associate salaries and they are around $4k per week. Not a bad summer gig if you can get it.
I would imagine that smaller firms would like to get some free help. I'm not sure how the official program with the school works, but that would be the place to start to look for internships. My advice would be for her to try to find a paying summer job as well as considering internships. One undergrad summer, I got a paying job with a law firm. It was just as a general office helper, not anything substantively legal, but I learned a lot. I also made some good connections. I had a couple of the lawyers write recommendations for my applications to the law schools from which they graduated. In other words, they helped me fool the law schools into believing that I was qualified to go there ... and it worked!
I would imagine that smaller firms would like to get some free help. I'm not sure how the official program with the school works, but that would be the place to start to look for internships. My advice would be for her to try to find a paying summer job as well as considering internships. One undergrad summer, I got a paying job with a law firm. It was just as a general office helper, not anything substantively legal, but I learned a lot. I also made some good connections. I had a couple of the lawyers write recommendations for my applications to the law schools from which they graduated. In other words, they helped me fool the law schools into believing that I was qualified to go there ... and it worked!