We find in several places in the Torah that the right hand (as well as the right side in general) is considered the more prestigious one. For example, at the end of the book of Genesis,1 we find that Jacob insisted on placing his right hand on the head of Ephraim while blessing him because of his tribe's future greatness. In fact, we are instructed to use our right hand (or right side) for many religious rituals. Several examples:

(Note: Some of these examples apply only to a right-handed person. More details on this later on in this article.)

  1. We are instructed to use our right hand (or right side) for many religious ritualsWhen purifying the metzora (a person with a skin ailment described in Leviticus), the kohen puts a mixture of oil and sacrificial blood on his right thumb and big toe.2
  2. The mezuzah is affixed on the right side of the doorway.3
  3. A scribe must write Torah Scrolls and other holy writings with his right hand.4
  4. We cover our eyes with our right hand when saying the Shema (in order to enhance concentration).5
  5. When washing hands upon arising or before eating bread, we start with the right hand.6
  6. We hold the kiddush cup in the right hand.7
  7. When blowing the shofar, we hold the horn to the right side of the mouth.8
  8. Some have a custom to clasp their hands while praying the Amidah (as a sign of supplication)—the right hand over the left.9
  9. When holding a Torah Scroll, we hold it on our right side (over the right shoulder).10
  10. When the chazzan (prayer leader) goes from the front area of the synagogue to the bimah (reading table), or vice versa, he takes the path to his right.11
  11. While saying a blessing on a food or mitzvah, we hold the item in the right hand.12
  12. During the chalitzah ceremony, the shoe is removed from the right foot of the brother of the deceased husband,13 with the widow using her right hand to do so.14
  13. When the priests turn towards the community to issue the Priestly Blessing, and then when they turn back to face the Ark after the blessing, they turn towards their right.15
  14. When serving in the Holy Temple, a kohen uses his right hand while performing any service.16

In Non-Ritual Matters

The right side is also given precedence in mundane activities. Several examples:

  1. The right side represents the side of goodWe clothe our right arm, leg and foot before the left arm, leg and foot, respectively.17 When removing our clothes, we do the opposite. We remove the left arm, leg, etc., from their respective garments and only then de-clothe the right. It is considered respectful that the right side remain clothed longer.18
  2. We wash the right arm, etc. before the left.19
  3. If on the road and one has a choice which way to go and is unsure what to do, one should turn to the right.20

The Reason

We show deference to the right side because the Torah specifies to use the right side on various occasions.21 The Me'iri22 explains that the right side represents the side of good, and by giving it precedence we remind ourselves to follow the right path. Kabbalistically, the right side represents the side of chesed (kindness), which is supposed to prevail over the left side, which represents gevurah (discipline).23

Exceptions

There are various exceptions to this rule. Some of them:

  1. We put tefillin on our left arm. (See below for more information regarding this.)
  2. Since in regards to tying the tefillin, the Torah gives importance to the left side, our sages said that when tying our shoes (or any other set of garments that need to be tied), we tie the left first.24
  3. When cutting the nails, we start with the left hand.25
  4. Men hold their tzitzit in their left hands when reciting the Shema in the morning, in order that the fringes should be against the heart.26
  5. When taking three steps back after completing the Amidah, we begin with the left foot (to indicate that it is difficult for us to depart from the presence of G‑d).27 Then, after taking the steps back, we first bow to the left (the right side of the Divine Presence whom we are facing), and then to the right.28
  6. When putting down one's head for tachanun (the supplicatory prayers after the Amidah) of the afternoon service, we rest our head on the left arm. This in order to honor the Divine Presence which is on our right side. In the morning, when praying with tefillin, we rest our head on the arm that is not garbed with tefillin.29
  7. We lean to the left at the Seder table, in order to free the right hand with which we eat. In addition it is considered dangerous (for health reasons) to lean to the right side.30
  8. When kindling the Chanukah menorah we begin with the left-most candle and procede to the right.31

Tefillin

We use the right hand to tie the tefillin on the leftWe don tefillin on the left arm because of the extra letter "hei" at the end of the word "yadchah" ("your arm") in Exodus,32 when discussing the mitzvah of tying tefillin on the arm. The Talmud33 therefore reads this word as "yad keiheh"—"the weaker arm." Other opinions in the Talmud learn this law from the juxtaposition of the command to write the mezuzah near the mitzvah of tefillin,34 teaching us that the hand used for writing is the hand that should be used to tie the tefillin. This means that we use the right hand to tie the tefillin on the left.

Several reasons are suggested as to why the left arm is chosen for tefillin:

  1. Because the right arm is generally used for mundane tasks, the left arm is chosen for this mitzvah.35
  2. The right (more dexterous) arm is suitable to bind the tefillin on the left arm.36
  3. One of the reasons for tefillin is to recall the Exodus,37 and we bind the tefillin on the arm to recall "G‑d's strong arm" that He used to punish the Egyptians. The "strong (punishing) arm" is G‑d's left one.38
  4. The tefillin help us subjugate our hearts (and minds) to G‑d. As such, it's appropriate that they be placed on the left side—opposite the heart.39
  5. The right side represents physical strength. The left side represents intellectual achievement (as signified by the fact that the heart is on the left side). We place the tefillin on the left side to indicate that we are trying to overcome our physical desires through our intellectual understanding (of G‑d).40
  6. We put the tefillin on the weaker side to teach us that we have no power to accomplish anything on our own; whatever we achieve is only with the strength given to us by G‑d.41

Tefillin for a Left-Handed or Ambidextrous Person

The Talmud says42 that a left-handed person puts the tefillin on his weaker arm,43 i.e., his right arm.44

An ambidextrous person puts tefillin on his left arm.45 If he uses his right arm for writing and he does everything else with his left arm, or vice versa, there's disagreement between various halachic authorities regarding the correct arm for putting on tefillin.46 In practice, in the first case one wears the tefillin on the left arm; whereas in the second case, one puts them on the right arm.47

Left-Handed People with Regards to Other Mitzvot

Mitzvot that are done with the right hand, a left-handed person does with his left handIn most cases, those mitzvot that are done with the right hand (or side), a left-handed person does with his left hand. Since his left hand is stronger, it represents the same thing that the right hand represents for a right-handed person.48

The following things49 should be done by a left-handed person on/with his left side:

  1. Clothe and wash the left side of the body first.50
  2. Wash the left hand first when washing for bread or upon arising in the morning.51
  3. Hold the kiddush cup in the left hand.52
  4. Hold the lulav in the left hand and the etrog in the right hand.53
  5. Step back after the Amidah with the right foot first (if he is left-footed).54
  6. Hold food or mitzvah items in the left hand while reciting the blessing.55

The following things, however, should be done by a left-handed person in the same way that a right-handed person does them:

  1. Mezuzah on the right side of the doorway.
  2. Cover the eyes with his right hand when saying Shema, so that he can hold his tztitzit with his left hand—opposite the heart.
  3. After the Amidah, bow to the left side first (corresponding to the right side of the Divine Presence).
  4. Put his head down for tachanun on his left arm (for the same reason).
  5. Lean to the left at the Seder, for health reasons as mentioned above.56
  6. Hold the shofar to the right side of the mouth.57
  7. A left-handed kohen turns around to bless the congregants the same way a right-handed kohen does.58
  8. Hold a Torah scroll on his right side.59
  9. Walk to the right as he walks to the bimah or the Ark, if he is a chazzan carrying the Torah.60