Leather Making is a rather cruel and destructive process. On one hand it is cruel to the animals being killed for their skins on the basis that they are being killed for their skins in the first place and because they are often raised in (if they aren't killed while they are young) cruel conditions that would cause great public outcry if practiced on human subjects.
On the other hand, it is commonly stated that over 95% of leather in the United States is chrome tanned. Chrome tanning is the process of treating leather so that it will not bio-degrade. This process used to be done with vegetable oils, but is now done with a variety of much more dangerous chemicals.
Below are some links related to Leather making and its cruel destructiveness:
What's wrong with Leather, Wool and Silk?
One Company's leather-making process
Below are some links to help you avoid supporting cruelty by buying non-leather and fake leather products:
Pangea Vegan Store
Cars with Non-Leather Interiors
Guide to Alternatives To Leather