"Law class three" in Engpsh can be referred to as "Law Faculty Class 3".
This naming convention is commonly used in universities, where the name of a class often includes the faculty or department it belongs to, followed by the class number.
Example sentences:
"I'm studying in Law Faculty Class 3."
"Law Faculty Class 3 is having a lecture on contracts tomorrow."
Translation:
"我在法学三班学习。"
"法学三班明天有一节关于合同的讲座。"