29 (1) the length and nature of previous service, to assure such sharing of exposure to hazards as the national security and military requirements will reasonably allow; (2) family responsibilities; and (3) employment necessary to maintain the national health, safety, or interest. The Secretary of Defense shall prescribe such policies and procedures as he considers necessary to carry out this subsection. He shall report on those policies and procedures at least once a year to the Committees on Armed Services of the Senate and the House of Representatives. § 674. Standby Reserve (a) Units and members in the Standby Reserve may be ordered to active duty (other than for training) only in time of war, of national emergency declared by Congress, or when otherwise authorized by law. (b) I n time of emergency— (1) no unit in the Standby Reserve organized to serve as a unit or any member thereof may be ordered to active duty (other than for training), unless the Secretary concerned, with the approval of the Secretary of Defense in the case of a Secretary of a military department, determines that there are not enough of the required kinds of units in the Ready Reserve that are readily available; and (2) no other member in the Standby Reserve may be ordered to active duty (other than for training) as an individual without his consent, unless the Secretary concerned, with the approval of the Secretary of Defense in the case of a Secretary of a military department, determines that there are not enough qualified members in the Ready Reserve in the required category who are readily available. § 675. Retired Reserve A member in the Retired Reserve may, if qualified, be ordered to active duty without his consent, but only as provided in section 672 (a) of this title. § 676. Retention after becoming qualified for retired pay Any person who has qualified for retired pay under chapter 67 of this title may, with his consent and by order of the Secretary concerned, be retained on active duty, or in service in a reserve component other than that listed in section 1332(b) of this title. A member so retained shall be credited with that service for all purposes. § 677. Reserve officers: use of in expansion of armed forces VVlien an expansion of the active armed forces requires that officers of the reserve components who are not members of units organized to serve as such be ordered as individuals to active duty (other than for training) without their consent, the services of qualified and available reserve officers in all grades shall be used, so far as practicable, according to the needs of the branches, grades, or specialties concerned.