A love of history is very useful for studying law and politics. For one thing human nature doesn't change. Lord Acton's dictum that "power tends to corrupt, absolute power corrupts absolutely" was true in Ancient Greece and Rome; in Medieval England - and is true today (which is why law is needed to curb these tendencies).
History is particularly useful for understanding Common Law systems - such as those in the UK and USA. It can explainthe background to current practice - and makes certain odd behaviour - in Parliament and Congress - understandable.
Websites relating to the institutions of Government have history links - follow the links below -
UK Parliament
UK Supreme Court
US Congress - House of Representatives
US Congress - Senate
US Supreme Court