Under Article 2 of the Uniform Code of Military Justice, members of the Army and Air National Guard are not subject to the UCMJ unless they have been called to FEDERAL active duty service. This means that members of the National Guard cannot be punished (Court-Martial or Article 15) for missing weekend drills or failing to show up for the two weeks of annual training. This is because, unless called up to Federal active duty service, the National Guard belongs to the individual STATE and not the federal government. However many states have enacted state laws which mimic the UCMJ articles for Guard members performing state service.
In all cases, whether Guard or Reserve, members ordered to Extended Active Duty (EAD) -- such as for a deployment to Iraq or Afghanistan -- are subject to the UCMJ. Guard and Reserve members who refuse or fail to comply with EAD orders, or go absent while on EAD are treated the exact same way as active duty members who go AWOL.
What happens if a Guard or Reserve member fails or refuses to show up for weekend drill? The services don't generally court-martial Reservists who fail or refuse to participate in drill. What the particular service:
Army Reserves and National Guard
Under Army Regulation 630-10, Chapter 5, Army Guard and Reserve members who refuse to report to Initial Active Duty Training (IADT) are discharged for "entry level performance and conduct." Participation in weekend drills for Soldiers who have not yet gone to Basic/AIT is completely voluntary ( Army Regulation 135-91, Chapter 3), so these members who refuse or fail to attend unit drill are not considered "unsatisfactory participation." Members who report for IADT and then go AWOL are treated the same as active duty members who go absent.
After IADT, an Reservist who has accrued in any one-year period a total of nine or more unexcused absences from scheduled drill, or who misses Annual Training (AT) are considered "unsatisfactory participants." What happens then is up to the unit commander. If the unit commander feels the member still has to potential to be deployed, the commander can transfer the member to the Individual Ready Reserve (IRR). The commander can also impose a grade reduction in conjunction with the transfer. If the commander feels the member does not have potential to participate in deployments, the commander initiates discharge action. Most such discharges are characterized as other-than-honorable conditions (OTHC).
The Army National Guard belongs to the STATE, not the Federal Government. Because of this, individual state laws may apply. I've been receiving more and more emails lately about individual STATE Army National Guard commands issuing STATE arrest warrants (for AWOL) for recruits who refuse to ship out to basic training, or fail to attend drill, ever since the end of 2008. To my knowledge, while threats have been made, nobody has yet been sent to state prison for such. Whether or not, such recruits could be subject to state imprisonment in the future, remains to be seen.
Air Force Reserves and National Guard
Air Force procedures are covered by Air Force Instruction 36-3209, and Air Force Manual 36-8001. Reservists who have been in the service for less than 180 days are considered to be in "Entry Level" status. Entry Level airmen who refuse to participate in weekend drill or refuse orders to IADT are almost always discharged. Most such discharges are characterized as "Entry Level." However, Reservists who go AWOL during IADT are processed the same as active duty members. p]Reservists who have nine or more unexcused absences from weekend drill in a one year period, or who fails or refuses to complete the two-week annual training are considered "unsatisfactory participants." The commander has several options. The commander can delay or defer promotion or impose an administrative demotion. The commander can involuntarily call the member to active duty for a period not to exceed 45 days. If the member has not completed their Military Service Obligation (MSO), the commander can even involuntarily recall the member to active duty for a period not to exceed a total of 24 months (the total includes any active duty time the member may have performed previously, such as deployment, basic training, or technical schools). Failure or refusal to comply with such orders to involuntary active duty constitutes AWOL, and the member is treated just as active duty members are. The commander may also transfer the member to the IRR. Finally, if the commander determines that continued Reserve service is not in the best interest of the USAFR, the commander may initiate discharge action. Most such discharges are characterized as OTHC.
Under COMNAVCRUITCOMINST 1130.8F, The Navy Enlisted Recruiting Program, paragraphs 6A-6 and 6A-7, members of the Navy Reserve, who have not yet started IADT, who refuse to participate in drill or IADT orders are discharged as an uncharacterized Entry Level Separation (ELS). Members who go AWOL while in IADT are treated the same as active duty personnel who go AWOL.
BUPERSINST 1001.39F, Chapter 11 describes the criteria for unsatisfactory performance in the Navy Reserves. Reservists who have nine or more unexcused absences in a one year period or fail to complete AT are considered unsatisfactory performers. If the commanding officer believes the circumstances that caused the Reservist to be an unsatisfactory participant have been resolved, he/she can place the member on six months probation. Otherwise, the commander can recommend transfer to the IRR. Finally, the commander can initiate discharge proceedings for the reason of "unsatisfactory participation." According to MILPERSMAN 1910-304, such discharges are usually characterized as Honorable or General (Under Honorable Conditions).