All noncitizens entering the U.S. are required to present themselves to a USCIS immigration officer for inspection.  This inspection meant that they will be assessed and that they must demonstrate the right to enter the country based on approval obtained prior to entry in the U.S.  If you do not have an approved means for entering the United States, then the Customs and Border Patrol or USCIS officer may refuse entry to you.

If you have entered without inspection (EWI) and without the proper documentation, there are a limited number of legal immigration options available to you.  If you or your spouse EWI, that means that you do not have legal immigration status in the United States.   That also means that you cannot file to change or adjust your status, as you do not have a legal status to begin with.  It is not possible to adjust status even if you marry a U.S. citizen or have U.S. citizen parents or children that will petition for them. However, there are a few exceptions that might allow an adjustment of status. The two most common are the LIFE Act and a waiver implemented in new immigration law as of 2012.