Is it even legal for people to make false claims for chargebacks?

It's happened multiple times now to sell stuff on ebay where a buyer would receive the item and anywhere from a week-a couple of months, I'd get a notification of said buyer trying to chargeback when the item has been with them for quite some time now.

Thankfully all this time just providing paypal with the tracking # showing item has been shipped to them has been enough to negate their false claims, but I'm just worried for a time when it won't.