Twice a month from several Roanoke church basements, a handful of volunteers dial up voters, urging them to read all three sentences of the Nov. 7 constitutional amendment on marriage.

Roanoke volunteer Ron Biagiarelli encouraged citizens to vote against the amendment but if he encountered opposition he didn't spar.

"I'm hoping you'll read the whole amendment," he said.

"Then, you'll get a good idea of what it is saying before you cast your vote."

These days, many people are reading the entire amendment, resulting in a duelfest of lawyers who disagree about the "unintended consequences" for all unmarried Virginians.

Supporters say the amendment is vital to protect Virginia's ban on same-sex marriages from court challenges. Opponents say the measure enshrines discrimination into the state constitution, and is so broad that it reaches beyond marriage to potentially undermine the legal rights of all unmarried Virginians.

Responding to requests from five lawmakers in the General Assembly, Attorney General Bob McDonnell on Thursday issued a 13-page opinion in his attempt to settle any uncertainty on the legal ramifications of the amendment. He maintained that the wording of Virginia's amendment is similar to the wording of 12 of the 20 states that have passed constitutional amendments. McDonnell said the amendment will not affect contracts, insurance, wills, advance medical directives or shared equity agreements between unmarried individuals. Nor, in his opinion, will it modify the application and enforcement of Virginia's domestic violence laws.

McDonnell, in a teleconference Thursday with reporters, said his support of the amendment didn't color his legal opinion.

"The intent of the amendment is clear. The first sentence defines marriage as solely the union between one man and one woman. The second and third sentences collectively prevent attempts to establish same-sex marriage, or similar relationships that attempt to create marriage-like unions by any other name," McDonnell wrote in the opinion.

"I can find no legal basis for the proposition that passage of the marriage amendment will limit or infringe upon the ordinary civil and legal rights of unmarried Virginians."

The Commonwealth Coalition, a group that is leading the fight against the measure, has enlisted about 130 lawyers so far to sign a 70-page memorandum drafted by Arnold & Porter, a Washington, D.C.-based law firm, that said the amendment goes beyond Virginia's existing ban on same-sex marriage.

The bipartisan group signing the petition included former Virginia attorneys general Stephen Rosenthal and Anthony Troy, both Democrats, as well as Wyatt Durrette Jr., an unsuccessful Republican nominee for governor in 1985.

"This exceedingly broad and untested language is the most expansive such proposal ever to have been put before the voters of any state," the memo states.

Lawyers who signed the petition concurred with the "significant and largely unpredictable legal consequences" of the proposed amendment. The firm's work on the memorandum was valued as an $190,642 in-kind donation to the Commonwealth Coalition, according to Claire Guthrie Gastanaga, who heads the anti-amendment effort.

"The bottom line is we have dueling legal memos," she said. "Any time you have reasonable lawyers taking completely opposite positions on the consequences of a proposed constitutional amendment, voters should do the smart and conservative thing and vote 'no.' This is a legal Pandora's box. It is unpredictable and we shouldn't be putting it in our constitution."

McDonnell said he "would strenuously disagree" with Arnold & Porter's finding that the Virginia amendment is more expansive than other states'. "I cannot comment on why other lawyers use words such as 'broad' and 'expansive.' Marriage is between a man and a woman. Any marriage look-alike, if they bestow the rights and benefits of marriage, will not be valid in Virginia."

Gov. Tim Kaine, who opposes the amendment, would not respond directly to McDonnell's opinion. But his view on the effects of the amendment's second and third sentences was very different. Kaine said he could support the amendment if it were limited to the first sentence.

"These are such broad and vague terms that, once you get out of the first sentence, I don't know what the language means," Kaine said. "There are an awful lot of folks who are lawyers of good faith and have the same integrity as Bob McDonnell who have looked at this language and said they're completely confused about what those two sentences mean."

Victoria Cobb of Va4marriage, which supports the amendment, welcomed McDonnell's opinion.

"Now that the legal concerns have been answered, Virginians can focus on the real issue: How we are going to define marriage for future generations? The General Assembly, the attorney general and the Virginia State Board of Elections have dismissed the opponents' baseless, unintended consequences argument; the people of Virginia should do the same," she said.

And 4th U.S. Circuit Judge Harvie Wilkinson, who is favored by conservatives, wrote an opinion piece, published Sept. 5 in The Washington Post, that says "the chief casualty in the struggle over same-sex marriage has been the American constitutional tradition."

Blacksburg lawyer Virginia Cochran, who spent 17 years with the Pulaski County public defender's office, has signed the Commonwealth Coalition's legal petition.

"The lawyer in me says this doesn't make legal sense," she said. "I feel very strongly -- on practical, legal, historical and social grounds -- that it is just a bad amendment."

Staff writer Michael Sluss contributed to this report.