I stole this from Noel's blog, taken from Protestants for the Common Good:

The Presidential Prayer Team is currently urging us to: "Pray for
the President as he seeks wisdom on how to legally codify the
definition of marriage. Pray that it will be according to Biblical
principles. With any forces insisting on variant definitions of
marriage, pray that God's Word and His standards will be honored by
our government." This is true.

Any good religious person believes prayer should be balanced by
action. So here, in support of the Prayer Team's admirable goals,
is a proposed Constitutional Amendment codifying marriage entirely
on biblical principles:

A. Marriage in the United States shall consist of a union between
one man and one or more women. (Gen 29:17-28; II Sam 3:2-5)

B. Marriage shall not impede a man's right to take concubines in
addition to his wife or wives. (II Sam 5:13; I Kings 11:3; II Chron
11:21)

C. A marriage shall be considered valid only if the wife is a
virgin. If the wife is not a virgin, she shall be executed. (Deut
22:13-21)

D. Marriage of a believer and a non-believer shall be
forbidden. (Gen 24:3; Num 25:1-9; Ezra 9:12; Neh 10:30)

E. Since marriage is for life, neither this Constitution nor the
constitution of any State, nor any state or federal law, shall be
construed to permit divorce. (Deut 22:19; Mark 10:9)

F. If a married man dies without children, his brother shall marry
the widow. If he refuses to marry his brother's widow or
deliberately does not give her children, he shall pay a fine of one
shoe and be otherwise punished in a manner to be determined by law.
(Gen. 38:6-10; Deut 25:5-10)

G. In lieu of marriage, if there are no acceptable men in your
town, it is required that you get your dad drunk and have sex with
him (even if he had previously offered you up as a sex toy to men
young and old), tag-teaming with any sisters you may have. Of
course, this rule applies only if you are female. (Gen 19:31-36)