Probably the most influential paper Gruen wrote during this period was never published. It set-off the Australian 'tariff compensation' debate in the late 1960s. The arguments were taken up in the 1970s generating considerable professional interest and controversy. Gruen pointed to the way in which tariffs for manufactures imposed costs on export industries, particularly agricultural industries. As an early and strong advocate of lower levels of industry assistance, Gruen's point was not to advocate additional assistance for farmers so much as to challenge the idea that farmers might have low levels of assistance removed before manufactures had higher levels of assistance removed. He caviled at the "attitude ... that anything any farm pressure group asked for was ipso facto unjustifiable". Gruen then commissioned Professor Peter Lloyd to write the survey of Australian economics of protection which would survey the tariff compensation debate. Lloyd had been one of Gruen's main opponents in the tariff compensation debate and his survey argued that the case for tariff compensation had been overstated – including in a Green Paper on Rural Policy in 1974 of which Gruen was a co-signatory. Gruen later agreed with Lloyd's analysis on the point.