"declare on behalf" is a correct and usable phrase in written English.
It means to announce or state something on someone else's behalf or representing them. Example: The lawyer will declare on behalf of his client that he is innocent.
I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part.
I would like to declare on behalf of my coauthors that the work described herein was original research that will not be submitted elsewhere and not under consideration for publication elsewhere.
At the four matches on anti-discrimination days – 30 June and 1 July – national team captains will declare on behalf of all players that they "wholeheartedly reject racism or any kind of discrimination, whether on or off the field of play.
"Governments of the industrial world," Mr Barlow declared, "on behalf of the future, I ask you of the past to leave us alone.
Ben-Gurion declared on behalf of the Jewish Agency: "We shall fight [beside Great Britain in] this war as if there was no White Paper and we shall fight the White Paper as if there was no war".
Justice Hugo Black, celebrated as a liberal by many scholars, declared on behalf of the majority that "when under conditions of modern warfare our shores are threatened by hostile forces, the power to protect must be commensurate with the threatened danger".
"I declare on their behalf our peaceful support for the youth revolution and that we are going to fulfill our complete duty in keeping the security and stability in the capital," General Ahmar told Al Jazeera on Monday.
World War II created further controversy concerning the British government's right to declare war on behalf of the Scottish people.
"We are not here to divide Spaniards... but if someone tries to declare independence on behalf of a part of Spain's territory, that cannot be done because it is beyond their powers," said Rafael Catalá.
I see no reason why we will not be able to compromise.' Roach had not arrived in Vegas for this war of words, but Richardson feels comfortable in declaring on their behalf that there will be no confusion in the Hopkins corner between himself and his co-trainer.
On the contrary, as the papal secretary of state declared on his master's behalf, "there is no doubt that whosoever sends her out of the world with the pious intention of doing God service, not only does not sin but gains merit".
