There are laws that govern the art and trade of summoning. These are known as the summoner's creed. The creed itself contains laws but also advice.
I - The law of exchange and servitude
Any favor must be paid for in equal or greater value to the spirit who has served well it's summoner, likewise spirits shall repay in kind if he is over rewarded and so shall the magi.
This law, is the most important of all. You must ALWAYS pay back a spirit for what he has done, not only is it rude not to, it can lead you to gain a large amount of enemies. For example, if you were to insult a dove spirit, not only would many bird spirit be also insulted but so would peace spirit be.
If you compensate, the spirit will owe you one and if he over do it, you owe him more. Which often leads to very profitable games of favors tennis.
II - The law of sacred natures
No magi may command the spirits to break their own creed, for doing so is an insult to all of spirit-kind for they are our allies even if they sometimes oppose us.
This one, was touched in the live lesson. If a spirit breaks his own nature, he will vanish into nothingness, leaving a hole where the spirit's being should be. Some speculate that this may cause corruption amongst them.
III - The laws of dominion and respect
Only those with strength of will, wealth of knowledge and an abundance of power may dominate the other world. When bound, all spirits shall test their summoner in a way they see fit.
This one is very simple. Spirits in general don't like being commanded and are independent. They are how ever cooperative with those they trust and when a new spirit meets a summoner, they will test their summoner to see if they can be entrusted with the other world's powers.
IV - The law of oaths, truthfulness and obedience
One may bind himself and the spirit into a contract, when a pact is done, lies become impossible and words become laws. Neither man nor spirit may break their word willfully for they swore on their own volition.
The concept here can be hard to understand but it is possible to create contracts or pacts with spirits, pacts are much more long term alliances and more defined than simple deals. One thing though is that one cannot lie or willfully go against his own word if he form a pact. It is a terrifying event when a novice form his first pact and lose control of his own actions. When under the effect, one physically cannot break his word.
V - The law of the spiritual home and relics
One shall obey the laws of the spirits and honor those who anchor with the material world. One shall not force a spirit into a fetish. One shall not willfully sell or give the fetish to another and one shall never imprison a spirit within a material prison.
As spoken before, it is possible to bind spirits into objects, but there is a code of conduct to it. First and foremost, don't bind a spirit to an item with it wanting to, it will only bring about disaster. Two, Although they are items, fetish rely on their owner to care for them and such are not to be handed out to others. The third one is ambiguous, since many use fetish to imprison harmful spirits. This one is often ignored or downgraded to not doing it permanently or only to very dangerous beings.