Customers who fail to check luggage

Customers who fail to check luggage by the applicable luggage acceptance times, risk having their luggage, and themselves, rerouted on the next available departure. Northwest retains the right, at its sole discretion, to allow check-in after these cut-off times when its representatives deem circumstances warrant. If checked luggage is accepted after above times, Northwest will not be liable for any expenses incurred as a result of luggage not being loaded on the same flight as the passenger. At minimum, Northwest will not assume the expense of delivering luggage to customers who check-in late or voluntarily separate from their luggage (see Delayed or Damaged Luggage for details). More at Baggage checking blog