What steps does Shylock take to ensure that Antonio is bound to the condition in the bond?

As Act I, Scene III, of William Shakespeare’s The Merchant of Venice begins, the character of Shylock, a Jewish moneylender, is introduced to the audience. The tense relationship between Shylock, Bassanio, and Antonio is quickly established despite some cordiality during the formalities. Bassanio’s invitation to Shylock to join him and Antonio for dinner is quickly and rudely rebuffed: “I will buy with you, sell with you, talk with you, walk with you, and so following, but I will not eat with you, drink with you, nor pray with you.” The topic of Bassanio’s need of money and of Antonio’s agreement to borrow that money on his friend’s behalf has been broached, and the moneylender is indeed interested.
The issue, then, becomes one of collateral, and it is here that the crux of the matter will be established, providing for the play’s dramatic tension and for the eventual and humiliating rejection of Shylock’s demand for payment from Antonio. The step that Shylock takes to ensure that Antonio is bound to the condition of the bond—a pound of the latter’s flesh in the event he is unable to repay the loan (“If you repay me not on such a day, / In such a place, such sum or sums as are / Express'd in the condition, let the forfeit / Be nominated for an equal pound / Of your fair flesh, to be cut off and taken / In what part of your body pleaseth me”)—is the court system. Shylock places his faith in the strength of his argument and the wisdom of the juror. Little does he know that Portia will intervene in the legal proceedings to his detriment. The trial in Act IV of The Merchant of Venice provides both for Shylock's final denunciation and for his heartfelt plea for justice considering his and his people’s history of dehumanization at the hands of the Christians who dominate Venice.

Shylock has a conversation with Antonio before they agree on the bond. First, Shylock ensures Antonio that he is able to provide the amount of money Bassanio intends to borrow from him. Next, Shylock mentions Antonio’s belief in lending money without charging interest and uses a story from the Bible to argue against it. Being a Christian, Antonio is much irritated by Shylock’s comments, saying that Shylock is like a devil who cites the Bible to suit his own purpose. Then Shylock further increases Antonio’s anger by pointing out that Antonio has insulted him many times before, and so asks why he should lend money to Antonio. Antonio says this is just a business transaction, and he will pay the penalty if he breaks the bond. After getting this word, Shylock puts on a friendly face and offers to lend him the money free from interest on the condition that he gets a pound of Antonio’s flesh if he fails to pay back. He further assures Antonio that it’s just a game and his flesh would be of no use to him. Antonio is probably prepared to pay a very high interest initially, but Shylock’s offer appears to be a lot more favorable than he has expected. He is also quite confident about this venture capital and does not take this condition seriously. Therefore, he gladly accepts it without hesitation and thinks Shylock grows kind.