The President's Commission on Organized Crime kicks off a week in which its attention is focused on cocaine trafficking. Today, it holds a press briefing at 10 a.m. in the State Department press briefing room. On Tuesday, Wednesday and Thursday, it will hold hearings in the Dean Acheson Auditorium at the State Department, also beginning at 10 a.m.

President Reagan is scheduled to meet with Tariq Aziz, the deputy prime minister of Iraq.

The Supreme Court returns from a two-week recess for three days of orders, opinions and arguments.

The National Alliance of Third World Journalists holds a press briefing on the Immigration and Naturalization Service's case against former Grenada ambassador Dessima Williams. The session is scheduled for 12:30 p.m. in Room 2227 Rayburn House Office Building. TUESDAY

The National Research Council releases the findings of a study it did for the National Highway Traffic Safety Administration on the costs and benefits of the national 55 mph speed limit. The news conference will be held at 11 a.m. in the lecture room of the National Academy of Sciences, 2100 C Street NW.

Federal Trade Commission Chairman James C. Miller III discusses the Reagan administration's regulatory agenda at a 12:30 p.m. National Press Club luncheon.

The Brookings Institution holds a press luncheon on income distribution and federal manpower policies at its headquarters at 1775 Massachusetts Ave.

The Arms Control Association holds a press luncheon briefing on recent developments by the United States and the Soviet Union in the command and control of nuclear forces. The session will be held at noon at 11 Dupont Circle. WEDNESDAY

Republicans are scheduled to select a Senate leader and the new chairman of the Foreign Relations Committee.

Two weeks of orientation begin for newly elected members of the House.

The Brookings Institution sponsors a forum entitled "Reforming Entitlements: Medicare and Health Costs" at its headquarters.

Defense Secretary Caspar W. Weinberger discusses the uses of military power at a National Press Club luncheon at 12:30 p.m. THURSDAY

The Commerce Department issues its report on October economic indicators.

The District of Columbia Institute of Certified Public Accountants sponsors a seminar at the Capital Hilton Hotel on trends and practices at the Securities and Exchange Commission. FRIDAY

The Federal Reserve Board issues its regular report on the condition of large commercial banks.