King used a financial metaphor to refer to the lack of compliance with the civil rights that the Declaration of Independence and the Reconstruction Amendments to the US Constitution (14th and 15th) included for all US citizens, without discrimination in terms of race.
King aimed to express that the US still owed, to its black citizens, the defaulted "promissory note" that Martin Luther King Jr. had mentioned and demanded in his remarkable "I have a Dream" speech, delivered in 1963. Instead of guaranteeing the promised rights of life, of freedom, and of the pursuit of happiness, black people had received a black check, one with no funds on it and were still waiting for the payment of such debt.
By the above statement, King was metaphorically addressing the noncompliance of the government with the civil rights as stated in the US Constitution for all US citizens as stated in the (14th and 15th) Declaration of Independence and the Reconstruction Amendments which was without race discrimination as at when declared.
King was trying to argue that the US owed its black citizens because it has not kept the promises made to the general American people because it has failed to guarantee the rights of life, right of freedom, and right of the pursuit of happiness.
Instead, the black community had been given a blank check and are left unattended to.
Many Arabs were dissatisfied with the Balfour declaration because they feared that their territories would be taken away and that they would be attacked because of different religion between them.
