There is a distinction in a bankruptcy between those assets which a debtor may keep and those that must be sold to fulfill their debt. They are classified as either exempt or non-exempt debts. Non-exempt debts are those that cannot be discharged and written off. Non-exempt debts include child support, alimony, court fines, any court settlement, luxury goods, any cash over $1000 that was borrowed 60 days or less from the filing of the bankruptcy, and any debt that arose through deception or fraud. Student loans are currently listed as non-exempt but are being assessed for the potential of being listed as exempt.
Bankruptcy, by nature, can be used for personal gain. The law tries to ensure that people do not profit through filing bankruptcy by avoiding something for which they became morally responsible for. This is why there are certain obligations that are kept such as any debt arising from fraud as well as child support or other court ordered payment. The sole purpose of bankruptcy is to get the debtor back in a position where they are able to pay for moral debts as well as those which arise organically through paying living subsidies and work necessities.