public Join GetJoin()

// GetDefinitionFromLayer - This code works even if the layer has a join to another table
private TableDefinition GetDefinitionFromLayer(FeatureLayer featureLayer)
{
  // Get feature class from the layer
  FeatureClass featureClass = featureLayer.GetFeatureClass();

  // Determine if feature class is a join
  if (featureClass.IsJoinedTable())
  {
    // Get join from feature class
    Join join = featureClass.GetJoin();

    // Get origin table from join
    Table originTable = join.GetOriginTable();

    // Return feature class definition from the join's origin table
    return originTable.GetDefinition();
  }
  else
  {
    return featureClass.GetDefinition();
  }
}