An old adage called “Miles’ Law” reads: Where you stand depends on where you sit. That’s a mild way of saying that politicians are often hypocrites. They profess to be acting on principle, but their perspective has a way of changing when they shift roles.

As Democrats solidify their power on Capitol Hill, after 12 years in purgatory, the wisdom of Miles’ Law is being demonstrated daily. Both parties have adopted tactics they condemned just a few months ago when employed by their rivals. And both have expressed shock — shock! — that the other side could be so perfidious.

Start with the decision of Senate Republicans to use a filibuster to block debate on a resolution criticizing the president’s Iraq policies. Last year, those very same Republicans were outraged at Democrats who filibustered several of President Bush’s nominees to the federal bench.

Republicans claim that nominations are a special case, that Democrats were abusing the Constitution and undermining the right of a duly elected president to shape the courts.

But Democrats rode to power last fall on rising disenchantment with the disaster in Iraq. By preventing debate on that issue, Republicans were doing exactly what they accused Democrats of doing — thwarting the will of the majority.

In fact, Republicans have suddenly fallen in love with the once-evil filibuster. Sen. Gordon Smith of Oregon threatens to use one if a spending bill fails to compensate rural counties containing large tracts of untaxable federal land. Sen. Pat Roberts might stall the same bill if it does not include $4 million to renovate an Air Force base back home in Kansas.

Democrats are equally disingenuous. Sen. Harry Reid, the party leader, was sputtering mad at the GOP filibuster over Iraq, charging that such a low tactic is only used “when you have something to hide or stall.” Which is exactly what the Democrats did on a number of Bush’s nominees: Hide their own weaknesses and stall for time.

A second demonstration of Miles’ Law: House Democrats rammed through six bills at the start of the session that were never considered by committees or subject to amendment. Yet for years, those same Democrats were furious and frustrated when Republicans leaders did the same thing to them.

This was a special case, argued the new speaker, Nancy Pelosi, we had to keep our campaign promises and we’ll never do it again. But it was a lame defense, given her frequent outbursts against similar Republican maneuvers.

Not to be outdone on the hypocrisy front, Republicans denounced Pelosi for following the GOP’s own playbook. The Democrats, wailed Rep. Adam Putnam, “missed (an) opportunity to really change the way that the House does business.” In other words, Putnam was offended that the Democrats had failed to correct the strong-arm tactics his own party had used for 12 years.

A third proof that Miles was right: Republicans have long depicted themselves as the “small government” party and condemned the “waste, fraud and abuse” under Democratic regimes. But under Republican rule, pork-barrel spending has exploded. The last budget contained more than 15,000 “earmarks” — legislative language directing Federal funds to lawmakers’ favored projects — costing almost $50 billion.

Republicans used these earmarks to cultivate special interests and generate campaign contributions in such a corrupt manner that two former Congressmen and several Hill staffers have already gone to jail. In six years, Bush never once used his veto to curb these excesses. But now that the Democrats are in power, and can use federal funds to reward their own supporters, the president has self-righteously demanded that the number of earmarks be cut in half.

House Democrats, to their credit, have wiped all earmarks out of the current budget. But according to The Politico, a new Web site, at least two of them are copying another Republican trick: using their influence to pressure a client (in this case, the state of Texas) into dropping lobbyists aligned with the rival party. Stan Brand, once a lawyer for House Democrats, lamented: “Why are Democrats revisiting the scene of the same crime that Republicans lost the House over?”

But the switch in power on Capitol Hill has not taught the White House any humility. On a whole series of issues, from conducting the war to keeping secrets, the administration continues to assert the primacy of executive power. We’ll do what we want, they say, and Congress can’t stop us.

Does Team Bush ever wonder how they’d react if those same claims for executive supremacy were made by, say, President Hillary Clinton?

(Steve Roberts’ latest book is “My Fathers’ Houses: Memoir of a Family” (William Morrow, 2005). Steve and Cokie Roberts can be contacted by e-mail at stevecokie@gmail.com.)