JOSEPH STASZAK - a Baltimore tavern owner, ward boss and former state senator - has never gained national renown. However, among watchers of Maryland politics and what might be called ethics-in-government buffs, Mr. Staszak has been held in special, wry regard as a king of one-man summation of what the problems are. He gained this status partly through his bluntness and political durability, but mainly through one incident several years ago. While he was in the state senate, Mr. Staszak aggressively sponsored a bill that directly helped his liquor business. A few people suggested that this might involve a conflict of interest.

"There is no conflict with my interest," Mr. Staszak said.

No one could have put it more plainly. That one sentence explained so much that it belongs in every political lexicon, right next to Tammany ward-heeler George Washington Plunkett's definition of "honest graft." ("I seen my opportunities and took 'em," Plunkett said.) Moreover, the Staszak sentence told ethics-law architects what they really should look out for: not the situations that, by some long stretch of imagination involve conflicts - but the ones in which the interests are so clear.

Any reference to the Staszak code now needs a footnote, though. It was provided in federal court in Baltimore last week, when Mr. Staszak pleaded guilty in - yes - a conflict-of-interest case. It seems that when he retired from the legislature and was appointed to the city liquro board, he said he had turned over the tavern to his daughter and son-in-law. In fact he had not. In fact, he made about $200,000 from the business while serving on the liquro board. And there he stood last week, admitting, "What I did was wrong."

Of course, the story needs one more sentence to be finished. But as a cautionary tale, it is already much improved.