The Sentencing Guidelines App can be purchased via any global AppStore and isn't tied to purchase within one territory.
If trying to reinstall the Sentencing Guidelines App is you receive an AppStore message "Your account is not valid for use in the US store" this indicates that your Country or Region has been temporary changed.
The first thing to try is to start iPad Settings > scroll down to iTunes & App Store, and tap your existing Apple ID and then tap Sign Out. Then sign-in again and Apple should correct your default App store to United Kingdom.
You can also check you default regions from the Apple iTunes App on your PC or Mac. You can download Apple iTunes from the Apple website here.
Start Apple iTunes and View Account in the iTunes Store. You will be prompted for your Apple ID and password.
Once logged in you can check or change the default Country/Region from your Apple ID Summary section.