The law firm was founded by Dr. Kurt Sandmann who practiced as a lawyer and notary, from 1924 to 1945 in Gdansk and Coburg and finally in Frankfurt am Main until 1976.

The firm was joined by the founder’s sons, Dr. Eberhard Sandmann (1958) and Dr. Egbert Sandmann (1968). Both acted first as lawyers and later from 1968 and 1976, respectively, also as notaries. Dr. Eberhard Sandmann died in 1995 and Dr. Egbert Sandmann retired at the end of 2006.

In 1994, a further family member, Peter Klinger, joined the firm having already established himself as a lawyer in Frankfurt am Main. Since 2008, he has specialised as a lawyer for tenancy and condominium law. In 2009 he was appointed as a notary.

In May 2010, the law firm expanded with the recruitment of Jörg Michaelis, lawyer and specialist lawyer for labour law since 1992.

In the year 2019, the lawyer Ingo Ley joined the law firm.