唐代中葉以降，法律形式變生了變化。唐格在這一變化過程中發揮了積極的變通作用。皇帝頒佈的制敕不具備法律的永久效力，只有經過一定的立法程式，將制敕加以刪定整理，去其重復抵牾，才能成為正式法律。開元以後制定的格後敕，是以開元二十五年所纂修的律、令、格、式為基準而制定的法，是一種綜合性法律規範。宋代承襲了唐代的做法，保持律的形式不變，而用外在的法律形式敕對其補充修正。而律在唐宋時期，自始至終都是在行的法律形式，從沒有被其他法律形式所取代。北宋前期，編敕是作為律、令、格、式的補充和修正而存在的。元豐以後，綜合性的敕不復存在，敕僅是刑事法律，只對律作補充修正，律保存不予改動。宋代不再用唐格的形式來補充修正律令。宋代的令與唐令是一脈相承的。唐格的法律形式，逐漸被宋代的格所取代。入宋以後，格已不具補充修改律令式等常法的功能。宋格是關於正確實施朝廷各項措施而設立的藉以比照和衡量的等級制度，入宋以後，宋式已不完全是令的實施細則，與唐式有著較大的差異。在唐律令體制下，例的運用規模並不大。例的大量應用，是在後來的宋代。宋代的申明實際上是朝廷立法機構對某些法律所作的解釋，具有補充、修改法的功能。但申明本身不能構成獨立的法律形式。宋代編集的所謂「指揮」，經立法程序，整理刪修後才能成為具有永久效力的法律。隋唐以來的律令制，入宋以後，並沒有退出歷史舞臺，宋代法律體制是唐律令制的延續和發展。

AbstractAfter middle period of the Tang Dynasty, the legal form changed. The Ge of Tang Dynasty had given play to the positive function of making changes according to specific conditions in the course of this change. The imperial decrees that were issued by the emperor did not possess the law to render a service for ever，only if they passed certain legislative procedure，they were made to put in order definitely and gotten rid of the content of repeating the contradiction among them.Then they would become the formal laws. Imperial decree made after the Kaiyuan years of the Tang Dynasty，which regarded the laws and decrees form of the 25th year of Kaiyuan as the datum, was a kind of comprehensive legal norm. Adopting the method of the Tang Dynasty, Song Dynasty kept the form of law arranged and adopted the external legal form --imperial decree -to amend it supplementarily. But the Law in the Tang and Song Dynasties was a current legal form all along. It had not been replaced by other legal forms. In the earlier period of the Northern Song Dynasty, the compiled imperial decrees existed with amending and supplementing to the Law, Decrees, Ge and Type. After the Yuanfeng years of the Song Dynasty, the comprehensive imperial decree had passed out of existence. The imperial decree was only a criminal law,which only amendd laws supplementarily. Law was kept and refused to change. In the Song Dynasty, supplementary and revising the form in which the laws and decrees did not adopt the Ge of the Tang Dynasty again. Amending and compiling the imperial decree in a large amount.The Orders of the Song Dynasty comes down in a continuous line with the Orders of the Tang Dynasty. The legal form of the Ge of the Tang Dynasty had been replaced by the legal form of Ge of the Song Dynasty gradually. During the Song Dynasty, the Ge did not possess and carry on the supplementary and function amendd to the current laws. The Ge of the Song Dynasty was a social estate system which was set up to be used for comparing and judging in order to implement every measure of imperial court correctly. During the Song Dynasty. The Type was not totally implementing regulations. There are greater differences between it and the one of the Tang Dynasty. Under the laws and decrees system in the Tang Dynasty, the application of the example was not big in scale. A large amount of application of the Example was in the Song Dynasty. In fact ,the statement in the Song Dynasty was a explanation made toward some laws of legislative body of imperial court. It had a supplementary function revising the laws. But the statement itself couldn't form the independent legal form. In the Song Dynasty,so-called " command " that was compiled compiled by the legislative procedure and put in order and amend.Then it could become a law that render a service for ever. Laws and decrees system of the Sui and the Tang dynasties had not withdrawn from the historical stage during the Song Dynasty. The legal system of the Song Dynasty was continuity and development of the system of laws and decrees of the Tang Dynasty.