U.S. secretary of state under President James Madison.

Smith grew up in Baltimore. He graduated in 1781 from the College of New Jersey (now Princeton University), studied law, and became a prominent and prosperous Baltimore attorney. From 1793 to 1801 Smith was active in Maryland politics, serving in both the state Senate and House of Delegates and in the Baltimore city council. Following Thomas Jefferson's election to the presidency, Smith was appointed secretary of the navy, largely owing to the influence of his brother.

During the Jefferson administrations, Smith successfully prosecuted the naval war against the Barbary States, and he conscientiously enforced Jefferson's embargo despite his personal opposition to the policy. It was during those years (1801–09), however, that Smith and Albert Gallatin (Gallatin, Albert), secretary of the Treasury, became foes.

When James Madison (Madison, James) became president, he wanted Gallatin to be secretary of state. But Samuel Smith and other prominent senators opposed Gallatin, and Robert Smith ultimately gained the post. Smith and Madison frequently disagreed—Smith objecting to the president's commercial restrictions, Madison unable to tolerate Smith's incoherent diplomatic communications.

In 1811, in a face-to-face confrontation, Madison accused Smith of inefficiency and of creating discord among members of the administration. The president offered Smith the position of minister to Russia in exchange for resigning. Smith hesitated, then refused, resigned, and retired. He spent the final 30 years of his life in Baltimore.