It is of course commonly known from Acts 5:29 (among other places, such as the book of Daniel) that government laws that would cause Christians to violate the law of God, should be ignored and disobeyed by Christians.
But what if there's a law that is unjust but does nothing to cause a Christian to sin? Is it still permissible for the Christian to refuse to obey said law?
Um... Well... I don't see any biblical support for such an exclusion. What we do see is several places where Christians are commanded to obey the government. Here is a sampling:
"Let every soul be subject unto the higher powers. For there is no power but of God: the powers that be are ordained of God. Whosoever therefore resisteth the power, resisteth the ordinance of God: and they that resist shall receive to themselves damnation. For rulers are not a terror to good works, but to the evil. Wilt thou then not be afraid of the power? do that which is good, and thou shalt have praise of the same: For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil. Wherefore ye must needs be subject, not only for wrath, but also for conscience sake. For for this cause pay ye tribute also: for they are God's ministers, attending continually upon this very thing. Render therefore to all their dues: tribute to whom tribute is due; custom to whom custom; fear to whom fear; honour to whom honour." ~Romans 13:1-7
"Submit yourselves to every ordinance of man for the Lord's sake: whether it be to the king, as supreme; Or unto governors, as unto them that are sent by him for the punishment of evildoers, and for the praise of them that do well. For so is the will of God, that with well doing ye may put to silence the ignorance of foolish men: As free, and not using your liberty for a cloke of maliciousness, but as the servants of God. Honour all men. Love the brotherhood. Fear God. Honour the king." ~I Peter 2:13-17
"I counsel thee to keep the king's commandment, and that in regard of the oath of God. Be not hasty to go out of his sight: stand not in an evil thing; for he doeth whatsoever pleaseth him. Where the word of a king is, there is power: and who may say unto him, What doest thou? Whoso keepeth the commandment shall feel no evil thing: and a wise man's heart discerneth both time and judgment." ~Ecclesiastes 8:2-5
Against the backdrop of these verses, it seems hard to argue that we should "resist the ordinance of God" by disobeying a law just because we find it to be unjust. Perhaps this makes us a tad uncomfortable, but I doubt this is the first command in the Bible that makes you feel a tad bit uncomfortable.
It would seem to me that we should obey the governing authorities in everything as long as doing so would not force US to be unjust in our dealings, or to otherwise sin against the commandment of God.