Why does Joe try so hard to ensure justice for the dead Chinese miners?

[[deleted user]]

Duty, even when he's lost an election and is police judge, not marshal. Loyalty, to the town that made him respectable, and to the in-laws who bought him.

[Lin]

And also to impress Grace, who's not in a mood to be impressed, and prove to her (and to Henry and Mary Stanton) that there can be second acts in an American life. But what a price! Would I have that much nerve? Not sure. Hope I never have to find out.

[Lin]

Also compensation, for all the compromises he has made, sending Grace away being the largest one.