A review of Yevamot 103-104 informs us that the Halitzah ceremony must involve the removal of a shoe from the right foot, while if – for whatever reason – the right foot is wearing a left shoe, the ceremony is valid ex post facto.
The question, of course, is why do these specific details matter? To answer, I would like to quote Rabbi Ari Shvat’s summary of the Malbim’s commentary to Devarim 25:9 who speaks about the symbolism of the shoe in the halitzah ceremony, stating that: ‘shoes symbolize one’s honour and desire (like in English: “Where he’s going”). When the widow takes off her former brother-in-law’s shoe from his right foot, she is as if it were stating that he has no honour and no desire to continue his brother’s family and name.’ (https://www.yeshiva.co/ask/57500)
As we know, the reason why a Halitzah ceremony takes place is where a brother-in-law and sister-in-law do not wish to marry following the death of her husband – who is his brother. And while the Torah certainly allows for halitzah to be performed, as Rabbi Shvat makes clear, ‘the ceremony is clearly meant to see his lack of family loyalty in a negative light’.
Given this, where a brother-in-law refuses to fulfil Yibum, though this is technically permissible, it is as if the Torah considers him to be in need of a lesson about ‘doing things right’. And I believe that this is the reason why the Torah is so particular about the details of the Halitzah ceremony, as if to say, ‘the way you have chosen to go is not really the right way. You have put your honor and desire above that of others. So let your bereaved sister-in-law teach you a lesson about the steps one should take in life – while showing you how to do things right.’