The Supreme Court, in its decision, suggested that such buffer zones would be constitutional, said First Amendment expert Steven Shiffrin, a law professor at Cornell University in New York.
Shiffrin said he has concerns.
"To me, this turns First Amendment values upside down. Someone could be carrying a sign praising the deceased or the courage of the family and that would be precluded," he said.
The laws also might be vulnerable because they are directed only at military funerals, rather than all funerals, Shiffrin said.
Oregon bill raises concern
The American Civil Liberties Union of Oregon objects to the state's bill, legislative director Andrea Meyer said.
The proposal violates the state's guarantee of free expression, which state courts have interpreted more broadly than the First Amendment, Meyer said.
"When you draft legislation targeting the particular speech of a particular party because you find that speech abhorrent, you run into real risks under the federal and state constitutions," she said.
Loew also reports for the Statesman Journal in Salem, Ore.