The books are with everything else hidden away. We don't have a law library, which is the entire point of abrogating everything. Otherwise, we'll be researching things for the next hundred years.
How are we going to know what needs reform and what doesn't if we a) don't have the books and b) don't have the time? That would be the entire point to wipe everything out and start from scratch while we can. Potter can do temporary decrees while we iron out the basics.
Also in case it escaped you're notice, we are in a period where nothing is illegal because there is no MLE or Wizengamot to enforce anything and no one knows the old laws.