In legal argument, avoid the third person “one,” as in “one could argue” or “one might add.” Too many “ones” arguing can lead to ball bouncing—a distracting batting back and forth of ideas. Also avoid “on the one hand” because it leaves the reader waiting for you to talk about “the other hand,” which is like leaving your reader to wait for an invisible shoe to drop.
Simply get to the point. Don’t say:
One could argue that the world is flat.
The world is flat.
Chances are that enough parties are already involved in your case, so you don’t need to add a mysterious, invisible player.