Some commercial leases will set forth the conditions under which a tenant may sublet space or under which the landlord can evaluate a potential subtenant or deny a proposed sublease. If your commercial lease does not have such restrictions, the landlord is generally required to not unreasonably withhold consent to a sublease. What constitutes “reasonable” withholding of consent will depend on the facts of the case, and you may need a commercial real estate attorney to help protect your rights.