The Emperor (Kaiser) has supreme authority over the Empire whether it be anything from military to economical matters. Recognized as the head of state and highest military official the Emperor however would be hard pressed to govern the Empires far flung bounderies. So a senatoral body the Senatorum Imperialis (Reichstag) or Imperial Senate is needed to help deflect the more onerous tasks of governing. However despite being able to pass laws and launch campaigns the Emperor has to get a majority vote when declaring out right war and passing larger edicts. The title of Emperor is hereditary in theory but Electoral when a heir is absent or more than one claiment comes forward. The current Emperor is Karl-Franz I who was crowned on April 15th 2010 after recieving a majority vote.
Although rather ineffective at times unless pressured the Imperial Senate in effect governs on a more managing scale. With its members usually being heads of Imperial organizations such as the Administratum, Inquisition, Armed forces or Federal representative. Originally founded during the Old Reich and surviving up to the current era the Reichstag has a much broader view then its counterpart the Bundestag. For it governs as a whole rather micromanaging which would slow down and grind almost to a halt.
The less prestigious and larger counterpart to the Reichstag is the Bundestag (Imperial Council) which does the micromanaging of the Empire. With each Province given a seat in the Bundestag it helps funnel information on every province to each respective organization and inturn govern more effectively at a more efficient amount of time.
The Lord Governor
The Lord Governors are charged with governing a single Province on the Emperors behalf and directly responsible for it. Each Lord Governor is elected from a selection of candidates that run for the office and supervised by the Bundestag then approved via the Reichstag. Such a title is for life or frequently upon retirement a new Lord Governor is chosen. The office grants its owner a large amount of power and it has occured when a Lord Governor has become corrupted and goes rogue or even traiter (they are usually crushed or flee). When it comes to the Military the Lord Governor has little to no power for the sake of granting him to much strength and only really can control the the Police to a certain extent within his own province. The only difference and very rare case would be the title of Lord Governor-General which is a combination of power incase of a lack of military officials or in dire circumstances.
Directly under Lord Governor are the Lord Mayors who control the seperate districts within a province. Districts within a province may very from a few to many in size, population and more commonly stability. Lord Mayors are elected every 3 years or for an extended time should the need arise (such as if a district is flooded in violence or war).
The lowest of the governing hierarchy, the Mayors govern and look after a village, town, or city. Serving for 2 years or if something should arise it may be shortend or extended.
The Codex Imperialis states that Imperial law is total and can only be changed with a three quarters vote of the Bundestag, Reichstag and the Emperors consent is given. Imperial law is often very broad and is more of an outline with the speculatives kept more akin to the Federal laws. The law is also quite strict when considering the laws of other countries but is fair to say the least.