How do I check whether a macbook is blacklisted or stolen?

Blacklisting only applies to cellular devices. Macs as such cannot be blacklisted.

There is no international database for stolen Apple products, so no possible way to know.

One way to tell that it is potentially lost or stolen is that the notebook will been locked and you will not be able to access it.

Report a lost or stolen Apple product - Apple Support

Another method, is to submit the MacBook's serial number to this Apple Support site. This will not tell you if it is either lost or stolen, only that Apple knows about the device:

• Find the serial number of your Apple product - Apple Support
• Your Service and Support Coverage - Apple Support

contact law enforcement. Apple does not provide this type of information.