In Egyptian mythology, Ma'at, pronounced as 'Muh-aht', is goddess of law, morality, and justice. Ma'at was supposed the stars, seasons, and the actions of both people and gods. Her first role in Egyptian mythology was the weighing of words that took place in the underworld, Duat.

Purpose 

Ma’at's purpose was to keep truth, balance, order, harmony, righteousness, morality, and justice. Ma’at weighed the heart of the deceased against her feather of truth on a scale during the journey to the afterlife.  She placed the dead man's heart on the other side while her husband Thoth wrote down the results of the scale to see if that person was good or bad and if they would have a happy afterlife or be eaten by the devourer. Without Ma’at, the universe would become chaos once again.   If the dead person’s heart was heavier than the feather, then it had done evil deeds like lying when it was alive.  When that happened, the heart was devoured by a monster and was not able to go to the afterlife.  If it was lighter than the feather, then it was allowed to go onto the afterlife.

Physical Description 
 
 
Ma’at had dark skin and hair. She was usually shown wearing a white linen dress. She, like Isis, was a winged goddess and she wore lots of armbands and necklaces made from gold and jewels. Her feather of truth was strapped to her head. Like the other gods and goddesses, she wore the black eye makeup around her eyes and on her eyebrows which is known as "kohl", which showed her high ranking status.

Law 

The chief judge in charge of the Egyptian law courts was known as “The priest of Ma’at.” He began court hearings wearing the feather of Ma’at. The person that won his case got to have the feather of Ma’at. The guilty party had violated Ma’at, and it was assumed that he or she would suffer failure, poverty, sickness, blindness and deafness, with the final judgment waiting in the court of the dead. Tomb robbery was considered one of the most heinous crimes, and might involve 100 strokes of a cane, five bleeding cuts added or brands as a sign of permanent dishonor. Often, the entire family of the guilty suffered as well. For example; when individuals were sentenced into exile, their children were automatically outlawed with them. Ma’at represented truth, order, balance and justice in the universe. This concept said that everyone, not including slaves, should be viewed as equals under the law. The king made sure that was carried out, and he/she would decide the case and the proper justice, maybe asking his viziers who often acted as judges. Even the lowliest fisherman was allowed to bring a legal case to the viziers.

Power and Magic 

All goddesses including Ma'at had power over the Egyptians, and different powers over the other gods. One of the powers Ma'at gave the gods was the ability to breath air. Like the water of life, Ma'at's potion brought an afterlife after death to the peaceful and law-abiding people, but death to violent and cruel people.  Ma'at was very powerful, but she still had limits to her powers. She could not make the sun travel through the sky like Ra could, she could not control the netherworld like Osiris could, and she could not make the stars shine like Nut could but she still had her own unique powers like her potion.

Worship 

The Pharaohs prime task in governing was to uphold Ma’at and they often held seated images of Ma’at in their hand to the gods, which indicated that the Pharaoh represented the divine order. The words “I have done Ma’at", were spoken by several Pharaohs and several others called themselves, “Beloved of Ma’at.” Even the gods were sometimes shown praising Ma’at. People were interested in how they could please her but they also were afraid of her. It was said that a small image of Ma’at was more pleasing to the gods than piles of rich offerings. It was also said that a little truth was more welcome than huge bribes.

Temples 

There was only one temple for Ma'at in Karnak but she was still worshiped in all Egyptian temples. In every Egyptian temple one area was called the hall of two truths or the hall of Ma'at. In the hall of two truths Ma'at weighed a man's heart against the feather of truth to see if the man would have an afterlife or his heart would be eaten by, the devourer.

Ma'at as a principle 

Ma'at as a principle was at least partially codified into a set of laws, and expressed a ubiquitous concept of right from wrong characterized by concepts of truth and a respect for and adherence to a divine order believed to be set forth at the time of the world's creation. 

The doctrine of Ma'at is represented in the declarations to Rekhti-merti-f-ent-Ma'at and the 42 negative affirmations listed in the Papyrus of Ani:

Declarations to Rekhti-merti-f-ent-Ma'at 

Verily I have come to thee, I have brought to thee Ma'at.
1.
2. I have not done iniquity to mankind.
3. Not have I done harm unto animals.
4. Not have I done wickedness in the place of Ma'at.
5. Not have I known evil.
6. Not have I acted wickedly.
7. Not have I done each day and every works above what I should do.
8. Not hath come forth my name to the boat of the Prince.
9. Not have I despised God.
10. Not have I caused misery.
11. Not have I caused affliction.
12. Not have I done what is abominable to God.

13. Not have I caused harm to be done to the servant by his chief.
14. Not have I caused pain.
15. Not have I made to weep.
16. Not have I killed.
17. Not have I made the order for killing for me.
18. Not have I done harm to mankind.
19. Not have I taken aught of the oblations in the temples.
20. Not have I purloined the cakes of the gods.
21. Not have I carried off the offerings of the blessed dead.
22. Not have I fornicated.
23. Not have I defiled myself.
24. Not have I added to, not have I diminished the offerings.
25. Not have I stolen from the orchard.
26. Not have I trampled down the fields.
27. I have not added to the weight of the balance.
28. Not have I diminished from the weight of the balance.
29. Not have I carried off the milk from the mouth of the babe.
30. Not have I driven away the cattle which were upon their pastures.
31. Not have I captured the birds of the preserves of the gods.
32. Not have I taken the fishes [with bait] of their own bodies.
33. Not have I turned back water at its season.
34. Not have I cut a cutting in water running.
35. Not have I extinguished a flame at its hour.
36. Not have I violated the times for the chosen offerings.
37. Not have I driven back the cattle of divine things.
38. I have not repulsed God in his manifestations.
I, even I, am pure. Times four.

42 Negative Confessions 

1. Not have I done wrong.
2. Not have I despoiled.
3. Not have I robbed.
4. Not have I slain men: twice.
5. Not have I defrauded the offerings.
6. Not have I diminished [oblations].
7. Not have I despoiled the things of the god.
8. Not have I spoken lies.
9. Not have I carried off food.
10. Not have I afflicted [any]
11. Not have I committed fornication.
12. Not have I made to weep.
13. Not have I eaten my heart.
14. Not have I transgressed.
15. Not have I acted deceitfully.
16. Not have I desolated ploughed lands.
17. Not have I been an eavesdropper.
18. Not have I set my mouth in motion [against any man].
19. Not have I raged except with a cause.
20. Not have I defiled the wife of a man.
21. Not have I defiled the husband of a woman.
22. Not have I polluted myself.
23. Not have I caused terror.
24. Not have I committed offense
25. Not have I inflamed myself with rage.
26. Not have I made deaf myself to the words of right and truth.
27. Not have I caused grief.
28. Not have I acted insolently.
29. Not have I stirred up strife.
30. Not have I judged hastily.
31. Not have I been an eavesdropper.
32. Not have I multiplied my words upon words.
33. Not have I harmed, not have I done evil.
34. Not have I made curses of the king.
35. Not have I fouled water.
36. Not have I made haughty my voice.
37. Not have I have I cursed God.
38. Not have I committed theft.
39. Not have I defrauded the offerings of the gods.
40. Not have I carried away offerings from the beatified ones.
41. Not have I carried off the food of the infant, not have I sinned against the god of the town.
42. Not have I slaughtered the cattle divine.

Notes

References 
Budge, E. A. Wallis. The Egyptian Book of the Dead: (The Papyrus of Ani) Egyptian Text Transliteration and Translation. New York: Dover Publications, 1967. Originally published in 1895.
Budge, E. A. Wallis. The Gods of the Egyptians: Studies in Egyptian Mythology - Volume 1. New York: Dover Publications, 1969. Originally published in 1904.
Collier, Mark and Manly, Bill. How to Read Egyptian Hieroglyphs: Revised Edition. Berkeley: University of California Press, 1998.
Faulkner, Raymond. The Egyptian Book of the Dead. San Francisco: Chronicle Books, 1994.
Mancini, Anna. Ma'at Revealed: Philosophy of Justice in Ancient Egypt. New York: Buenos Books America, 2004.
Strudwick, Helen. The Encyclopedia of Ancient Egypt. Singapore: De Agostini UK, 2006.

Other websites 
Principles of Ma'at (negative confessions)
Egypt: Law and the Legal System in Ancient Egypt by Mark Andrews
A list of the 42 Principles of Ma'at 
A series of discussions on the meanings of the 42
http://www.touregypt.net/godsofegypt/Maat.htm
http://www.philae.nulakhet/akhet/netjerum.htm#maat.htm
http://www.touregypt.net/godsofegypt/maat.htm
http://www.aelives.com/gods.htm 
http://www.philae.nulakhet/religiond2.htm
http://www.touregypt.net/featurestones/law/.htm

Egyptian gods and goddesses