The process by which lower federal court judges are nominated by the President and confirmed by the Senate has, in recent decades, been of continuing interest to Congress. During Senate debates in the 112 th Congress over judicial nominations, differing perspectives have been expressed about the relative degree of success of a President's nominees in gaining Senate confirmation, compared with nominees of other recent Presidents. Senate debate often has concerned whether a President's judicial nominees, relative to the nominees of other recent Presidents, encountered more difficulty or had to wait longer, before receiving consideration by the Senate Judiciary Committee or up-or-down votes on confirmation. Of related concern to Congress have been increases in recent years in the number and percentage of vacant judgeships in the federal judiciary and the effect of delayed judicial appointments on judicial vacancy levels. This report seeks to inform the current debate in three ways: first, by providing a statistical overview of President Obama's nominees thus far to U.S. circuit court of appeals and U.S. district court judgeships, and of any actions taken on their nominations by the Senate Judiciary Committee and the full Senate; second, by using various statistical measures to compare the success to date of President Barack Obama's judicial nominees in advancing through the Senate confirmation process with the success of the judicial nominees of the four most recent preceding Presidents (Ronald Reagan, George H.W. Bush, Bill Clinton, and George W. Bush); and third, by identifying various factors which might help explain differences or variations found in judicial appointment statistics across the five presidencies. Most of the statistics presented and discussed below were generated from an internal CRS judicial nominations database. Other data sources, however, are noted where appropriate. The statistics account only for nominations made by Presidents Reagan through Obama to U.S. circuit court and U.S. district court judgeships established by Congress under Article III of the Constitution. On March 12, 2012, an agreement was reached by Senate Majority Leader Harry Reid and Senate Republican Leader Mitch McConnell identifying 14 lower court nominations that would receive up-or-down Senate confirmation votes by May 7, 2012. The statistics provided in this report include Senate confirmation of the 14 nominees subject to the March 12, 2012, agreement between the two Senate leaders, the confirmation of two additional district court nominees on May 14, 2012, and the confirmation of Paul J. Watford to the Ninth Circuit Court of Appeals on May 21, 2012. Article III, Section I of the Constitution provides, in part, that the "judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish." It further provides that justices on the Supreme Court and judges on lower courts established by Congress under Article III have what effectively has come to mean life tenure, holding office "during good Behaviour." Along with the Supreme Court, the courts that constitute the Article III courts in the federal system are the U.S. circuit courts of appeals, the U.S. district courts, and the U.S. Court of International Trade. As mentioned above, this report focuses on nominations made by President Obama and other recent Presidents to the U.S. circuit courts of appeals and the U.S. district courts. Outside the report's scope are the occasional nominations that these Presidents made to the nine-member Court of International Trade or to the territorial district courts. These courts take appeals from federal district court decisions and are also empowered to review the decisions of many administrative agencies. Cases presented to the courts of appeals are generally considered by judges sitting in three-member panels. Courts within the courts of appeals system are often called "circuit courts" (e.g., the First Circuit Court of Appeals is also referred to as the "First Circuit"), because they are divided into 12 geographic circuits and one additional nationwide circuit, the Federal Circuit, which has specialized subject matter jurisdiction. Altogether, 179 appellate court judgeships are currently authorized by law. The First Circuit (comprising Maine, Massachusetts, New Hampshire, Rhode Island, and Puerto Rico) has the fewest number of authorized appellate court judgeships (i.e., 6), while the Ninth Circuit (comprising Alaska, Arizona, California, Hawaii, Idaho, Montana, Nevada, Oregon, and Washington) has the most, 29. In this report, nominations to U.S. courts of appeals judgeships are frequently referred to as "circuit court nominations." These are the federal trial courts of general jurisdiction. Altogether, there are 91 Article III district courts: 89 in the 50 states, plus one in the District of Columbia, and one more in the Commonwealth of Puerto Rico. Each state has at least one U.S. district court, while some states (specifically California, New York, and Texas) have as many as four. Altogether, 673 Article III U.S. district court judgeships are currently authorized by law. Congress has authorized between 1 and 28 judgeships for each district court. This section provides a statistical overview of President Obama's appointments to U.S. circuit courts of appeals and U.S. district courts from January 20, 2009, through May 31, 2012. It begins with a statistical summary of the current confirmation status of President Obama's circuit and district court nominees. It then examines the extent to which circuit and district judgeships in each of the nation's judicial circuits are filled by appointees of President Obama. It concludes by comparing the number and percentage of circuit and district court judgeships that were vacant at the start of the Obama presidency with current vacancy statistics. Table 1 provides a statistical summary of the confirmation status of individuals nominated by President Obama to U.S. circuit and district courts between January 20, 2009, and May 31, 2012. Thus far, President Obama has nominated 41 persons to circuit court judgeships. Of the 41, 29 (70.7%) have been confirmed by the Senate, 6 (14.6%) have failed to be confirmed after their nominations either were withdrawn by the President or returned to the President and not resubmitted to the Senate, and 6 (14.6%) currently have nominations pending (2 in the Senate Judiciary Committee and 4 on the Senate Executive Calendar). President Obama has nominated 150 individuals to U.S. district court judgeships. Of the 150, 117 (78.0%) have been confirmed by the Senate, 6 (4.0%) have failed to be confirmed after their nominations either were withdrawn by the President or returned to the President and not resubmitted to the Senate, and 27 (18.0%) currently have nominations pending (15 in the Senate Judiciary Committee and 12 on the Senate Executive Calendar). In total, 146 (or 76.4%) of President Obama's circuit and district nominees were confirmed between January 20, 2009, and May 31, 2012. Overall, President Obama's 29 confirmed circuit court nominees currently fill 16.2% of the nation's 179 authorized circuit court judgeships, while his 116 confirmed district court nominees currently fill 17.2% of the nation's 673 authorized Article III district court judgeships. President Obama's confirmed judicial appointees, however, are not distributed uniformly across geographic circuits. The opportunity to appoint circuit and district judges to a particular circuit depends upon the vacancies which exist when a President takes office or which subsequently arise during his presidency. As a result, there will be variation at any given time both in the number of nominees a President succeeds in having confirmed across geographic circuits and in the percentage of judgeships across circuits which are held by appointees of a President. Figure 1 and Figure 2 reveal notable variation among the 12 geographic circuits and the Court of Appeals for the Federal Circuit in the number of U.S. circuit and district court judgeships held by President Obama's appointees as well as in the percentage of circuit and district judgeships in each circuit held by his appointees. As Figure 1 shows, President Obama has appointed the greatest number of U.S. appeals court judges to the Fourth Circuit (i.e., 6 confirmed nominees), the Second Circuit (5), the Ninth Circuit (4), and the Federal Circuit (3). In contrast, as of this writing, no nominees of President Obama have been confirmed to either the Eighth Circuit Court of Appeals or the U.S. Court of Appeals for the D.C. Circuit. The Eighth Circuit, comprising Arkansas, Iowa, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota, does not (as of May 31, 2012) have any existing vacancies. There are presently, however, three vacancies on the D.C. Circuit, including Supreme Court Chief Justice John G. Roberts's former seat on the court. If no appointment to the D.C. Circuit occurs before January 20, 2013, President Obama will be the first President in more than 50 years who has served a full four-year term without having a single nominee confirmed to this court. As for U.S. district courts, Figure 1 shows that President Obama has had the greatest number of judges appointed to district courts located within the Ninth Circuit (22 confirmed district nominees), the Second Circuit (13), and the Fourth Circuit (13). Under President Obama, at least one district court judge has been appointed in each circuit. The two circuits with the fewest confirmed Obama district court nominees are the First Circuit (3) and the Sixth Circuit (4). The circuits in the federal judiciary vary in the number of appellate and district court judgeships that are statutorily authorized. Consequently, the circuits in which a President appoints the largest (or smallest) number of nominees might not always correspond to the circuits in which his appointees also constitute the largest (or smallest) percentage of sitting judges.