Frontrunning is a crime because it's acting on privileged information. It's in the same boat as insider dealing. They have that privileged info because of their

Frontrunning is a crime because it's acting on privileged information. It's in the same boat as insider dealing. They have that privileged info because of their fiduciary relationship so it is relevant. What the HFT guys are doing is not frontrunning because anyone can get hold of the same information they have (for a price). That information is not privileged (assuming deep pockets != privilege) so it's not frontrunning. They're getting to the trade first because they're technically quicker than the routers the banks are using.