The South China Morning Post reported recently on jailhouse inventors, a topic that you may have first read about here. According to the SCMP and Beijing Youth Daily, various provinces have different commutation schemes for inmates that file patents, which are based on provisions in the criminal law permitting commutation based on meritorious service (Criminal Law, Art. 78).
As with their policy “cousin”, patent subsidy and innovation tax incentive programs, not all inventions are treated equally for purposes of obtaining government benefits. For example, according to 2005 Provisional Opinions on Specific Questions on Commutation of Sentences in Jiangsu,《关于审理减刑案件若干问题的意见（试行）》 one invention patent is equal to one utility model patent or three design patents.
Similar to patent subsidy programs, there is also any number of patent agents pursuing this type of business. However, the best practice for would-be inventors is likely if the convict or his/her representative finds a patent agent familiar with the practice of the local prisons as practices may vary.
Why the increased interest in jailhouse inventors? Probably the press has picked up on this issue with the December 9, 2014 decision of the Beijing Second Intermediate People’s Court which reportedly granted one year’s commutation of the sentence of the former Chinese Football Association Vice President Nan Yong. Nan Yong was granted 4 patents in 2012 and 2013 for: a soccer practice device, a portable goal, assembly of mobile terminal supporting frames, and a desktop computer monitor.
Considering the large size of the US prison population (about 600,000 more than China), is this an untapped resource for encouraging innovation in the US :)?
Update of May 18, 2019: Here is a recent article from the Shanghaiist about a death row rapist who may have earned early release by patenting a new manhole cover design.