You must automatically contact proper authorities (police, etc.) and keep the client there as long as possible, so they cannot harm the neighbor.
To your first question--James Madison is widely known as the architect of the US Constitution (Although in reality it was the result of team work by 56 delegates).
To your second question--The six key principles outlined in the US Constitution are:
1. Popular Sovereignty (i.e. democracy or rule by the people)
2. Limited Government (i.e. again, democracy or the government can only do what the people instructs it to do)
3. Separation of Powers (there are three branches of power: legislative, executive, and judicial AND they are separate from each other)
Which brings me to...
4. Checks and Balances (each branch "checks and balances" the other two branches' power. For ex: the US President can veto congressional bills, Congress can ratifies judicial nominees, and the Supreme Court decides on the constitutionality of congressional bills).
5. Judicial Reviews (the judicial branch reviews governmental actions)
6. Federalism (there is a federal and a state government. These are separate from each other)
Well, capitalism is not always a free-market economy.
A typical capitalism is a free-market economy, which means that the market itself (buyer and sellers) can decide the prizes and terms of services.
In capitalism, the capital is privately, and not state owned. But capitalism can also come in other forms: of social democracy with partially free market, and with other forms which include corporations having controls over the market.
