After receiving his secondary education at the gymnasium at Eisleben in Prussian Saxony, Gneist entered the Friedrich Wilhelm University of Berlin in 1833 as a student of jurisprudence, and became a pupil of the famous Roman law teacher Savigny.

He used his "wanderjahre" ("journeyman's year") for the purposes of comparative study; upon on his return in 1844, he was appointed extraordinary professor of Roman law in the University of Berlin, and thus began a professorial connection which ended only with his death.

The first fruits of his activity as a teacher were seen in his brilliant work, Die formellen Verträge des heutigen römischen Obligationen-Rechtes (Berlin, 1845).

Pari passu with his academic labors he continued his judicial career, and became in due course successively assistant judge of the superior court and of the supreme tribunal.

Although his candidature for election to the National Assembly of that year was unsuccessful, he felt that the die was cast, and, deciding upon a political career, retired from his judicial position in 1850.

Entering the ranks of the National Liberal Party, he began both in writing and speeches actively to champion their cause, now busying himself pre-eminently with the study of constitutional law and history.

He was parliamentary reporter for the committees on all great financial and administrative questions, and his profound acquaintance with constitutional law caused his advice to be frequently sought, not only in his own but also in other countries.

He was a jurist of a special type: to him law was not mere theory, but a living force; and this conception of its power animates all his schemes of practical reform.

As a teacher he exercised a magnetic influence, not only for the clearness and cogency of his exposition, but also because of the success with which he developed the talents and guided the aspirations of his pupils.