In a judgment of August 14, 2007 ( 9 AZR 18/07 ), the Ninth Senate dealt with the scope of the weekly teaching obligation during the partial retirement of a teacher employed by the Free State of Saxony. In a judgment of August 14, 2007 ( 9 AZR 18/07 ), the Ninth Senate dealt with the scope of the weekly teaching obligation during the partial retirement of a teacher employed by the Free State of Saxony. If the employer has made binding use of this right in accordance with Section 106 Sentence 1 GewO, this can have an impact on the duration of the weekly working time, which is to be used as the basis for subsequent partial retirement. If the employee owed the increased teaching performance immediately before the transition to partial retirement, this must be taken as the agreed previous working time in accordance with the collective agreement regulating partial retirement work (TVATZ), which was contractually referred to as a collective agreement supplementing the BATO. According to § 3 para. 1 subparagraph 1 TV ATZ, the average weekly working hours during part-time retirement employment are half of the previous weekly working hours. If the parties stipulate a specific number of hours as the average weekly working time with reference to a collective agreement assessment provision, this does not constitute a constitutive regulation. The partial retirement employee can request to be employed with the working hours resulting from the correct application of the collective bargaining standard. If the correct calculation results in a higher number of hours, the part-time employee can request employment with this number of hours