THE FEDERAL EAGLE
The federal eagle is one of Germany's three state symbols. Its origin goes back to the Holy Roman Empire. The counsel Gaius Marius set the eagle as a standard for the legions in 104 BC. Throughout history, the eagle represented a divine emblem for kings and emperors. In 1433, the eagle was used by German emperors for the first time. The Holy Roman Empire of the German Nation came into an inheritance of the symbol after the former Holy Roman Empire had fallen apart. The double-headed eagle was reserved for German emperors and the regular eagle for German kings.
During the German Revolution of 1848/49, the St. Paul's church assembly chose the double-headed eagle as their new coat of arms to tie in with the Holy Roman Empire of the German Nation. Still, the revolution failed, and both the black, red, and gold flag and the coat of arms of 1848 were dismissed. In 1871, the single-headed eagle became the coat of arms of the newly formed German Reich to link to the Prussian tradition. The federal eagle comes in different appearances. The heraldic rules only regulate that the eagle's head has to look to the right (from a heraldic point of view as depicted in the picture above) and mustn't have a crown. Also, the federal eagle must be levitating in the shield.
The Federal Eagle is protected by law, meaning that it is forbidden to use the state symbol in any form but official purposes, art, or education. It is also valid for a German flag that depicts the eagle. It can only be hissed by institutions representing the German government.