Our law firm focuses on personal injury law, but we also handle criminal defense cases. We have 1 location. Does it matter which practice area is chosen first in our Google Business Page (formerly Google My Business)?
It matters. If you have a chance to rank and display in Local Search results for your primary category, personal injury in this case, you definitely want "personal injury attorney" selected as your primary category. If PI is selected as a secondary category it significantly decreases that page's ability to rank in the 3 Pack / Local Search results.
In this case I would probably make your secondary category Criminal Defense Attorney, then a 3rd category could be "law firm".