I guess you could take the nullification route for all the good it will do you. You can also just vote to aquit without any reason or explanation required. Jury nullification does nothing and has no impact on what you would consider an unconstitutional law. The law will still be applied and people will still be charged and convicted of violating it. I guess there may be some emotional satisfaction in playing Chief Justice but it does not mean anything in the end.
Chief Justice John Jay, U.S. Supreme Court Georgia v Brailsford (3 Dallas 1, 1794)
"The jury has a right to judge both the law as well as the fact in controversy."- Samuel Chase, Supreme Court Justice 1804 signer of The Declaration of Independence. "The jury has the right to determine both the law and the facts."
Nobody is suggestion megalomania here, by, as you say, "playing Chief Justice". Merely desiring to know what our rights are as jurors. One day, it may be a knowledgable juror that saves you from being charged with an unjust law...not because you are guitly of what you were charged with, but the law behind the charges violated your Constitutional rights.
"...it does not mean anything in the end"
"Indeed, if juries do not have the right and power to nullify the law, we must face the fact that Harriet Tubman, one of the great heroines of American history, would and should have been guilty of multiple federal crimes by violating the fugitive slave laws. That is a morally revolting prospect, but judges today who reject nullification must confess that they would enforce the fugitive slave laws and convict Harriet Tubman. If they were to honestly admit as much, and hold themselves powerless to disobey unjust and morally despicable laws, they should be told that "obeying orders" was not accepted as a defense in the Nazi war crime trials at Nuremberg." (1)
"Until the middle of the 1800s, federal and state judges often instructed the juries they had the right to disregard the court’s view of the law. (Barkan, citing 52 Harvard Law Review, 682-616) Then northern jurors refused to convict abolitionists who had violated the 1850 Fugitive Slave Law. In response judges began questioning jurors to find out if they were prejudiced against the government, dismissing any who were. In 1852 Lysander Spooner, a Massachusetts lawyer and champion of individual liberties, complained "that courts have repeatedly questioned jurors to ascertain whether they were prejudiced against the government. . . . The reason of this . . . was that ‘the Fugitive Slave Law, so called’ was so obnoxious to a large portion of the people, as to render a conviction under it hopeless, if the jurors were taken indiscriminately from among the people." Modern treatments of abolitionism praise these jury nullification verdicts for helping the anti-slavery cause – rather than condemn them for undermining the rule of law and the uniformity of justice."
(2)