Jwalsh, engineering is an uncommon major for pre-law students. That isn't a bad thing, but law school involves a lot of reading, writing, and analyzing. These aren't skills that are stressed in an engineering curriculum, because you're learning a lot of technical and mathematical skills. Preparing for the LSAT also takes a good dedicated chunk of time, which you need to make sure you have available. Also, like you mentioned, engineering is a tough major. If it's not really what you want to do after you graduate, a lot of people don't feel like it's worth it to work through the program only to end up at the same place (like law school) as everyone else.
I'm not saying you can't do it, but a pre-law engineering major is quite rare in my experience.