According to the modern criminal law, those who are sentenced to imprisonment are exempt from hard labor, but those who are condemned to penal servitude can`t escape it. The punishment of imprisonment has been largely imposed on the political offenders. In this respect, the imprisonment of today are similar to chin ku of the Han Dynasty. Chin ku in the Han times means to disqualify a person from serving as an official or to degrade an official to lower status than that of the common people by deposing him from his post. The provisions on chin ku were enforced as a means to prevent an official from committing crime. chin ku was not only imposed on the official dismissed from his office in the course of struggle fom power, but also on his kinsmen that are so near to him in blood as to wear mourning dress for more than five months in memory of him, those who became officials by his recommendation or appointment, and his followers. There were once innocent people whose social status was too severely restricted to be qualified for officials. Among them were the merchant, the adopted husband who entered his wife`s family and worked for them in compensation for his marriage, and the commoner having less than 40,000 gian worth of property. Some historians hold that the merchants were degraded to the lowest class on the ground that they had been disqualified for public service since the early Han times. But we should remember that the provisions which kept them from entering officialdom were abolished in 119 B.C. during the reign of the Emperor Wu di. Thereafter they could be officials. That means their social status was raised to the common people. On the basis of the provision enforced in the reign of the Emperor Wen di that an adopted husband can not be appointed as an official, some historians assert that an adopted husband was degraded to a mere obligatory slave. But it is presumed that one who lived with his wife`s family was interpreted as an adoped husband, irrespective of whether he made an obligatory contract with his wife`s family. The provision in the reign of the Emperor jing di that the commoner having less than 40,000 gian worth of property couldn`t enter officialdom was not carried into effect from the next Emperor Wu di.