I recently completed going through the explanation of Sh. Abdul-Rahman al-Sa’di’s poem on Islamic legal maxims (al-Qawa’id al-Fiqhiyyah), also known as fiqh maxims. The explanation was done in Arabic by none other than Sh. Waleed El-Maneesee, a well-known Hanbali scholar residing in Minnesota, United States. The recordings to the explanation are available for free access on his website. For those interested in studying it in English, there is a series available by Dr. Jamel Ben Ameur available here.
Sh. Sa’di’s poem (منظومة القواعد الفقهية) is popularly taught around the world to teach students basics of the theory of legal maxims in Islamic law. It is a genre of Islamic sciences that focuses on general rules of fiqh which can be applied to a wide variety of particular situations. These maxims have been used by Muslim jurists for centuries to give verdicts (fatwas). They assist in the matter of ijtihad because they organize the branches of fiqh and categorize cases and it is a must for every Muslim jurist to have knowledge of it.
They are often written in short but expressive statements. They tend to express at times the goals and objectives of the Shari’ah and this is why some scholars treat this subject under the category of objectives of Islamic law (maqasid). Their wording can be excerpts from the Qur’an or hadiths but in most cases reflect the phraseology of leading jurists and have been refined with the passing of time. The maxims are purposefully put in precise words in order to make them easy to remember and derive rulings without having to delve deeply into the texts. They are a sort of shortcut to same rulings that can be applied in multiple similar-like scenarios. You can refer to my write up of it here for further discussion of its definition with examples.