Can you credit a card (e.g. prepaid gift or debit) that blacklists certain companies?

Even you could create a card that promised to do this, and the system could be configured to do this there would be huge gaps in the system.

In the United States (and maybe other countries) there exist a set of cards that are configured to work only with merchants that fit in a set of merchant categories.

• In the case of a debit card linked to a Flexible spending account or a Health savings account, the merchant has to be a doctor, medical facility, or a pharmacy.

• For a debit card that is to be used to pay for commuting expenses, the merchant has to be a subway system, bus system, commuter train, or parking lot.

• Many colleges have also worked out a set of local vendors who allow the students to use their campus bucks at local restaurants, grocery stores, and other places.

In all these examples the use of the card is limited to specific merchant categories, or only to a set of local vendors who have signed up to participate in the program.

What you are proposing would be to filter by vendor. If restaurant E is evil, then your system would have to allow the use of the card at every restaurant but at Restaurant E.

While it sounds close to what the college systems have done, it would be harder to do, because it would involve kicking merchants out after they turned evil, and letting them return if they reformed their ways. You would have to set up your own network or get the big systems to allow you to do this.

But the biggest issue is that you would have to convince the merchants to subdivide your purchases into good and evil. If I was buying my groceries, and put on the belt dog food from the Evil dog food company, the system would have to allow me to buy with the card everything else. I would have to decide to skip that dog food purchase, get a different brand, or use another card or cash. Of course I hope the blacklist doesn't get to the flavor level. Either way the people in line behind me would not like me.

Something close to this is done with certain government benefit programs. Each item is identified as an acceptable use of the specified aid program money. These program do limit use to specific items, but also work with the vendors to identify all the items that meet the requirements.

What you are proposing would require this level of help from the merchants. If your card didn't get the support of the network and the merchants and only saw $123.00 from grocery store X, then evil purchases would easily be missed.