Why do they choose such a harsh penalty in romeo and Juliet?

Answer 1

I assume you are referring to the Duke's pronouncement that people found guilty of fighting in the streets are to be put to death. Basically, the situation was getting out of control and he had to resort to draconian measures to try to stop the incessant fighting (I mean, three civil brawls, all born of an airy word. I ask you!)

Answer 2

The harsh penalty in Romeo and Juliet serves to heighten the conflict and drama of the story. It escalates the stakes and emphasizes the deep divide between the two families, the Montagues and Capulets. Ultimately, the tragic consequences of the penalty highlight the destructive nature of feuds and vendettas.

Answer 3

He will have to live in Mantua, knowing that Juliet lives in Verona and he can's speak to her.