It's available here, from Howard. The introduction:

In this case, we must decide if our state statute limiting civil marriage to a union between a man and a woman violates the Iowa Constitution, as the district court ruled. On our review, we hold the Iowa marriage statute violates the equal protection clause of the Iowa Constitution. Therefore, we affirm the decision of the district court.

From the end of the opinion:

  We are firmly convinced the exclusion of gay and lesbian people from the institution of civil marriage does not substantially further any important governmental objective. The legislature has excluded a historically disfavored class of persons from a supremely important civil institution without a constitutionally sufficient justification. There is no material fact, genuinely in dispute, that can affect this determination.
  We have a constitutional duty to ensure equal protection of the law. Faithfulness to that duty requires us to hold Iowa's marriage statute, Iowa Code section 595.2, violates the Iowa Constitution. To decide otherwise would be an abdication of our constitutional duty. If gay and lesbian people must submit to different treatment without an exceedingly persuasive justification, they are deprived of the benefits of the principle of equal protection upon which the rule of law is founded.