(This Aug. 14 story has been corrected to reflect that the Missouri Attorney General's office is not involved in the case, in paragraph 6)

By Daniel Wiessner

(Reuters) - A federal judge in Missouri struck down on Wednesday the Republican-led state's rule limiting the ability of financial professionals to consider environmental, social, and corporate governance factors in giving investment advice.

U.S. District Judge Stephen Bough in Kansas City agreed with a trade group, the Securities Industry and Financial Markets Association, that the 2023 rule was invalid because it imposed requirements on investment banks and broker-dealers that do not exist in federal law.

The rule issued by Missouri Secretary of State Jay Ashcroft would require investment advisers who consider ESG objectives, such as combating climate change or supporting a social movement, to disclose them to customers and obtain their consent.

Bough said that along with its conflicts with federal law, Missouri's rule violated the free-speech rights of investment advisers and was so vague that it could not be enforced under the U.S. Constitution.

State officials "could have embarked on a public-information campaign to advance their desired message," wrote Bough, an appointee of former Democratic President Barack Obama.

Ashcroft's office hired private counsel to defend the rule and the office of Missouri Attorney General Andrew Bailey, a Republican, is not involved in the case.

SIFMA CEO Kenneth Bentsen said Missouri's rule was unnecessary and would upset the uniform nationwide regulation of the securities market guaranteed by federal law, which already requires financial professionals to act in the best interests of their clients.

"That means they cannot put their interests ahead of their customers' interests when recommending securities," Bentsen said in a statement.

Missouri's rule is part of a broader push by Republicans in some U.S. states to limit the growing consideration of ESG factors by businesses and investors, including employee retirement plans that collectively invest trillions of dollars.

The administration of Republican former President Donald Trump adopted a rule barring retirement plans from considering any "non-pecuniary" factors in making investment decisions. The Biden administration eliminated that rule, a move that is being challenged in court.