Deuteronomy, Chapter 25 is another list of arbitrary rules that leave me wondering what situation created a need for them in the first place?

Rule 1.  If a judge convicts someone as guilty in a dispute, the judge can issue no more than 40 lashes by a whip.  Anymore than that would be publicly humiliating.

Rule 2.  Don't muzzle an ox while he's working; in other words, let the ox eat while it works.

Rule 3.  When one brother dies, his wife must marry his brother (whether she likes him or not?).  It says, "If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not marry ... her husband's brother shall go in unto her, and take her to him to wife, and perform the duty of a husband's brother unto her."  A husband's duty, according to this passage, was just to have sex with his wife.

Rule 4.  If the MAN doesn't want to have sex with his brother's wife, then the wife should go to the elders, remove the man's shoe, and spit in his face.  Huh?

Rule 5.  When two men are fighting, and a wife helps her husband by grabbing the other man's balls, then she should have her hand chopped off.  What?!?

Rule 6.  Be honest when doing business with others.

Rule 7.  Hate the Amelekites. 

Okay, so in Deuteronomy Chapter 25 the rules are all over the map, and they're all arbitrary.  The one rule that is actually halfway decent is the sixth one I list above, which is Deuteronomy 25:13-15, about not cheating when doing business with others.  Letting an ox eat while it works is nice, but I'd be inclined to say its unimportant.  And the other stuff, stopping at 40 lashes, hating the Amelikites, chopping a woman's hand off for protecting her husband, is just wrong.  And weird!