As a landlord, can I terminate a commercial lease due to an unfit lessee?

As a landlord, you have the right to carve out certain pre-conditions to leasing your premises—such as a clean criminal background check or a credit check.

If you did not carve out these exceptions, you do run the risk of breaching a lease—particularly if the corporate tenant has been paying rent timely, not creating a fuss and the criminal activity has little to do with current operations (e.g., one of the partners was busted for a DUI eight years ago).

You may be able to work out an agreement with the tenant company whereby they voluntarily agree to leave ("surrender") the premises, so that you can take back the premises without a fuss. If thats the case, you'd want some assurances from the tenant's owners that they have sufficient voting rights and authority to make that decision without the third partner.

But all that should be clearly documented. Make sure you have able legal counsel helping you through this.