What did the Civil Rights Act of 1866 guarantee? Why did Congress and the president disagree over Reconstruction?

In 1866, Congress passed the nation's first Civil Rights Act. In the 1857 case of Dred Scott v. Sandford, the U.S. Supreme Court had ruled that black Americans were not citizens and could never become citizens. The Civil Rights Act of 1866 declared that all people born in or naturalized in the U.S.(except Indians) were citizens and were entitled to equal protection under the laws. It specifically declared that citizens could sign contracts, own property, testify in courts of law--civil rights that black Southerners had been denied under slavery. The law provided severe penalties--a fine up to $1,000 and jail terms of up to one year--for those who violated black Americans' civil rights. Once again, the president vetoed this law, and once again, Congress overrode his veto.