How can the WA-01 special election not be in the old district? Those districts will still be in effect until the 112th Congress adjourns for the last time, and this election will choose a Member of Congress who will serve only for the duration of the 112th Congress.

Consider, for example, a different scenario -- either Louise Slaughter (NY-28) or Tom Reed (NY-29) resigns. Would it be appropriate to simply not fill the seat, because New York will have only 27 districts in the 113th Congress, a time during which the special election winner won't be serving and the district won't even exist? Refusing to hold a special election in one of those districts (or IL-19, IA-05, LA-07, MA-10, MI-15, MO-09, NJ-13, OH-17, OH-18, or PA-19) would be logically consistent with holding the WA-01 special election using boundaries that the winner thereof won't represent.

Then there's the question of whether any of the candidates for the new WA-01 would try for a head start in Congressional seniority by running in the special election for the old WA-01. After all, you don't have to live in a Congressional District to run there.

According to RCW 29A.28.041(3), the special election's primary will take place in August, same as the new seat's primary. Ditto for the general election. Although I'm no lawyer, it seems to me that there is an ambiguity in RCW 29A.20.021(2), which states:

Excluding the office of precinct committee officer or a temporary elected position such as a charter review board member or freeholder, no person may file for more than one office.

On the face of it, that would preclude filing for both. But it could be argued that "Representative from WA-01" is actually the same office, in different timeframes (and representing different boundaries). Under this perhaps-tortured logic, double-filing might be OK.

Not that I think it would be wise for the new district's candidates to divide their efforts and/or confuse the hell out of the voters. But it's fun to consider logical puzzles such as this, to apply reductio ad absurdum to them.