In Shakespeare's The Merchant of Venice, how would one describe Venetian law and trade?

In Act 1, scene 3 of Shakespeare's The Merchant of Venice, Shylock discusses the law regarding trade in Venice that frustrates him. In an aside, he says the following:

"I hate him for he is a Christian;

But more, for that in low simplicity

He lends out money gratis, and brings down

The rate of usance here with us in Venice" (I.iii.37-39).

This passage provides a glimpse into understanding the law surrounding trade. First,...

In Act 1, scene 3 of Shakespeare's The Merchant of Venice, Shylock discusses the law regarding trade in Venice that frustrates him. In an aside, he says the following:

"I hate him for he is a Christian;

But more, for that in low simplicity

He lends out money gratis, and brings down

The rate of usance here with us in Venice" (I.iii.37-39).

This passage provides a glimpse into understanding the law surrounding trade. First, lending money and charging interest is legal in Venice. However, only Jews participate in this business because "usance" or "usury" is against Christian's beliefs. It is alright if a Christian borrows money from a Jew if he also agrees to pay the interest, or fees; but for the most part, Christians don't participate in the lending part of the business. Therefore, if a Christian like Antonio lends money to someone, such as Bassanio, he does not charge a fee or interest when his friend pays him back. This drives down the fees of interest for Shylock who does deal with "the rate of usance." This also makes Jews like Shylock mad because it hurts their business dealings and margins of profit.

Then, just like today, when someone borrows money, a contract is drawn up and is bound by, or supported, by the law. So when Shylock and Antonio appear before the Duke in Act 4, the written and signed contract is presented and remains binding even if it calls for a pound of Antonio's flesh closest to the heart. (Shylock calls the contract a "bond" throughout the play.) It is only when Portia cites a law that takes precedence over the details of Shylock's bond that the contract is broken. 

"The law hath yet another hold on you.

It is enacted in the laws of Venice,

If it be proved against an alien

That by direct or indirect attempts

He seek the life of any citizen,

The party 'gainst the which he doth contrive

Shall seize one half his goods; the other half

Comes to the privy coffer of the state,

And the offender's life lies in the mercy

Of the Duke only" (IV.i.342-351).

In this section, Portia shows Shylock that since he is an "alien," and seeks the life of a citizen of Venice, he must forsake all his goods and wealth to Antonio and the state. His life is also in the Duke's hands because of this crime. This is where Portia catches Shylock and saves Antonio.