The scramble to fill the seat on the Honolulu City Council left vacant by the death of Barbara Marshall tells you everything you want to know about the perils and possibilities of elective office in Hawai'i these days.

The past several elections have seen an alarming drop in the number of candidates filing for office and a clear pattern of avoiding a challenge to incumbents. Scores of offices go uncontested and the incumbent slides into another term.

But when a vacancy opens up, look out.

Who can forget the parade of candidates who showed up in 2006 when former Congressman Ed Case decided to run for U.S. Senate? Hawai'i has rarely seen such a lengthy list of qualified, intriguing candidates competing for one office.

It's true that for most of the candidates, the congressional bid was a no-lose proposition. They did not have to resign the office they held to run, though there was, of course, the possibility of damage to their political reputation and at least one candidate — former state Rep. Brian Schatz — did give up a relatively safe legislative seat to make the run.

Now, there is an unexpected vacancy on the Honolulu City Council and the stampede is on. The list of candidates includes two former council members — Steve Holmes and John Henry Felix — as well as a long list of community activists and political hopefuls.

It will be a strange election, since balloting will be by mail. Ballots go out to voters in Marshall's Windward O'ahu district (Waimanalo, Kailua, portions of Kane'ohe) around April 3, with voting to be concluded by April 23. The winner will serve out Marshall's term, which ends in January 2013.

Expect an even bigger stampede when Congressman Neil Abercrombie steps down to pursue his bid for governor. Technically, Abercrombie could fill out his term and still run for governor. But the speculation is that he will quit sooner than that, triggering not only a fall election for the full two-year term but also a special election to fill out the remainder of his current term. If the 2006 battle for the Case vacancy is any indication, this will be a wild free-for-all.

Since the state's resign-to-run law does not apply to candidates for federal office, this is an opportunity for state officials to test themselves without major risk.

The good news is that voters will get a far-from-usual chance to see a strong and diverse field of candidates. The bad news is that this opportunity happens far too infrequently.

Jerry Burris' column appears Wednesdays in this space. See his blog at blogs.honoluluadvertiser.com/akamaipolitics. Reach him at jrryburris@yahoo.com.