Gov. Mark Dayton rained vetoes on the post-session parade Tuesday, depriving the Legislature's GOP majorities of any claim to hope that the DFL governor might allow some portion of their slimmed-down 2012-13 state budget to become law.

The Republicans offered Minnesotans renewed vows of determination to avoid raising taxes, despite a $5 billion forecast deficit in the next two years.

Dayton countered with a blunt assessment of the consequences of the GOP's position.

He decried the Republicans' "extremely harsh and unfair" spending measures, their "intransigent" Tea Party faction and party leaders who reject compromise, and the "strong likelihood" that the impasse at the Capitol would lead to a government shutdown after July 1.

It made for a sobering day after to a legislative session that's remarkable for its lack of conclusive action. Legislators of both parties went home after Monday night's adjournment with the bulk of the session's work undone and with little to show for four-plus months of lawmaking labor.

Two early bills, an alternative pathway for teacher licensure and streamlining of environmental permitting rules, now stand out as leading achievements.

But the most prominent item on the 2011 session's list of accomplishments also may be the most divisive act by a Minnesota Legislature in many a year.

The House's approval Saturday night of a constitutional amendment banning same-sex marriage will trigger an 18 months-long campaign that's bound to be costly and emotional, and has the potential to be cruel and destructive.

As an amendment, it is out of the reach of Dayton's veto pen. Its next stop is the 2012 general election ballot.

This newspaper would have preferred not to let this pernicious genie out of the lawmaking bottle. Now that it is, Minnesotans should put their best efforts into its defeat. This amendment would embed discrimination into Minnesota's bedrock charter, turning a sizable majority into second-class citizens because of whom they love.

It's understandable that, for many voters, same-sex marriage evokes emotional, deeply felt responses.

For many who support the amendment, it's a religious and moral question, settled for all time by ancient scripture. Others are hung up on the word "marriage" and could support extending to same-sex couples all the legal rights that come with marriage under some other rubric, such as "civil union."

But opponents of the amendment, including the Editorial Board, believe that this is a matter of basic human rights. The U.S. Constitution obliges states to provide equal protection under the law to all citizens, regardless color, creed, religion -- or sexual orientation.

Strong arguments can be mustered against the amendment that don't involve pelting its supporters with insults and epithets. Among them: This state's economy and culture benefit from inclusivity.

Attitudes about same-sex marriage are changing rapidly; a constitutional ban would freeze today's thinking in time and could be a burden to future Minnesotans.

It's notable that while this state's GOP and DFL leaders differ strongly on taxing and spending -- and social issues including same-sex marriage -- their battles largely have been waged on the merits and with civility.

The schoolyard name-calling that characterized some of the worst moments at the Capitol in the last several years seldom surfaced this year. While a respectful tone is not sufficient to set a new state budget, it's often necessary for progress.

Minnesotans should approach the same-sex marriage debate with the same spirit of civility, verbal restraint and respect for their fellow citizens' heartfelt positions.

For our part, we'll aim to publish on these pages a range of respectful opinions, while arguing from this corner why the amendment must fail.

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