Need help with creating a dropdown that creates options in a separate dropdown

I'm a little familiar with scripting, and the research that I have done for help on this issue, I'm having a hard time locating.

I want to create a form where a dropdown list will have category law codes in it.  When that is chosen, a second drop downlist provides descriptions of the law codes within that category.   And then depending on the selection of the 2nd dropdown list, the form will provide the law code itself.

An example.  Ohio Revised Code has a category for Theft, which is 2913.  Another category is Drug offenses, which is 2925.  So the first dropdown would be each of these categories would be 2913, 2925, etc.

Then depending on which category is selected, the 2nd dropdown would contain a list of all descriptions in that category.  2913 has (just to name a few) Theft; Forgery; Identity Fraud.  2925 has (to name a few) Drug Possession; Drug Instruments Possession.  

Then the form would provide the actual law code itself depending on what the 2nd dropdown list is.  An example is if Theft is selected, then it would show "2913.02 A", or Identity Fraud as "2913.49 A 1".  Or Drug Possession would show "2925.11"

There would be a couple hundred criminal codes for the 2nd dropdown list.  An example is "Theft - without privilege to do so", then "Theft - beyond the scope", then "Theft - by Deception", etc, but each one of these has it's own code itself.  Theft - without privilege is 2913.02 A 1.  Theft beyond scope is 2913.02 A 2, Theft by deception is 2913.02 A 3.

so, the form would be to select the category, "2913" as an example.  Then select the description "theft by deception" then the form produces the criminal code "2913.02 A 3"

Any help would be appreciated.  Is there an easier way than what I have described?