Michael Fighting
"Michael…who standeth for…thy people," — Dan. 12:1-12

From the Code of Canon Law on Elections
Canon 160: The election of the Roman Pontiff is governed exclusively by the Constitution of Pope Pius X, "Vacante Sede Apostolica," December 25, 1904. In other ecclesiastical elections the laws of the following Canons are to be observed.
Canon 161: If the right to elect to a vacant office rests with an electoral college, the election, unless stated otherwise in the law, shall never be deferred for more than three months reckoned from the day on which notice of the vacancy was received. If the electoral college has neglected to hold the election within three months, the superior who has right of confirming the election, or to whom passes the right of appointment in default of the college, shall freely appoint a person to the vacant office.
Canon 162: Unless particular constitutions or customs regulate the manner of convoking the voters, the president shall convene all the members of the electoral college in the prescribed manner at a place and a time convenient to the voters. If the convocation is to be announced to each one personally, it suffices for validity, if the notice be addressed either to the place of domicile or quasi-domicile of the voters, or to the place where they actually stay. If one of the voters was neglected, and for that reason missed the election, the election is valid, but the person thus neglected may demand that the competent superior rescind the election provided the lack of notification and absence from the election is proved. The party retains this right even after the election has been confirmed, provided he can furnish legal proof that he forwarded his objection tot he competent superior within at least three days after obtaining knowledge of the election. If more than one-third of the voters were neglected in the convocation, the election is ipso jure invalid. The lack of notice does not invalidate the election, if those who were not called are nevertheless present. If the election is to an office which is to be held for life, the convocation of the electors made before the office was vacant has no legal effect at all.
Canon 163: The convocation having been legitimately made, the right to elect rests with those who are present on the day fixed in the notice, and no one has a right to vote either by letter or by proxy, unless the particular law rules otherwise.
Canon 164: Even though one and the same person may have the right to vote under several titles, he may nevertheless cast but one vote.
Canon 165: No one who does not belong to the electoral college, may be admitted, except in virtue of privileges legitimately acquired: otherwise the election is ipso jure null and void.
Canon 166: If laymen meddle in any way in the ecclesiastical election, or interfere with its canonical freedom, the election is ipso facto invalid.
Canon 167: The following may not cast a vote:

1. Persons incapable of a human act;

2. Persons under the age of puberty;

3. Persons suffering from censure or infamy of law, if such censure or infamy has been previously inflicted by a declatory or condemnatory sentence;

4. Persons who have joined at heretical or schismatical sect, or publicly adhered to such. This refers to Catholics who have fallen from the faith, as a similar phrase in Canon 542 was explained by the Committee for the Authentic Interpretation of the Code (October 16, 1919 AAS XI, 480);

5. Persons deprived of the active vote either through legitimate sentence of the ecclesiastical judge or by the common or the particular law;
If any one of the aforesaid persons is admitted to the election, his vote is invalid, but the election is valid unless it is certain that the elected would not have had the required number of votes without the illegal vote; and the election is invalid if a person excommunicated by a declatory or condemnatory sentence has knowingly been admitted to vote.
Canon 168: If any of the voters is present in the house in which the election takes place, but cannot be present at the election on account of ill-health, his written vote shall be taken by the tellers, unless particular laws or legitimate customs provide otherwise.
Canon 169: A vote is null and void unless it is (1) Free, wherefore a vote is null and void, if through grave fear or deceit, the voter was led directly or indirectly to cast his vote for a certain person, or for several persons separately; (2) Secret, certain, absolute and determinate. Conditions attached to a vote before the election are to be ignored.
Canon 170: No one can validly vote in his own favor.
Canons 171 to 178 deal with the particulars of an election
Canon 542, paragraph 1: Besides the regulations given in Canons 539-541 and others imposed by the constitutions of the various religious organizations, the following shall be observed:
Admission into the novitiate is invalid in the case of:

1. Persons who have lapsed from the Catholic faith into a non-Catholic sect;

2.

October 16, 1919: The Code Commission was asked: Whether the words: 'qui sectae acatholicae adhaeserunt', of Canon 542 are to be understood as applying to those who, moved by the grace of God, came into the Church from the heresy or schism in which they were born, or rather to those who fell away from the faith and joined a non-Catholic sect. Reply: In the negative in the first part; in the affirmative in the second part.
In other words, converts are not considered by the Canon, but those who were in the Church, but defected are. Canon 167/4: Qui sectae haereticae vel shismaticae nomen dederunt vel publice adhaeserunt;
Canon 542/1/1: Qui sectae acatholicae adhaeserunt;
Canon 167 appears to require more than Canon 542 to be incurred.
Canon 19: Laws which decree a penalty, or restrict the free exercise of one's rights, or establish an exception from the law, must be interpreted in the strict sense.

Canon 19 applies to Papal Elections, because Pope Pius XII's law, as well as previous laws are an exception to the general law given above.