The police have several "tools" at their disposal that would allow them to enter your home and arrest you without a warrant. BUT that doesn't mean they did so properly. You need to contact an attorney that can address these issues. It may be possible, depending on the facts, to file a motion to suppress to exclude evidence gathered by the police, based on an illegal search. Your attorney will know what to do.
It certainly is not a good spot to be in. However, even with the best of circumstances, you can be jailed on your 1st DWI. You definitely need a DWI Attorney to act as a go-between and take some of the heat off of you that you can't do yourself.
An "obstruction" charge is a reduced charge that is definitely preferable to a DWI on your record, however, there are many more factors to consider before you would accept an offer like that. Definitely do NOT accept any offer without having an attorney look at your case. It may be that there is something wrong with the DWI case that an attorney could get the case dismissed completely--you just don't know. This scenario happens many times when a prosecutor knows they have a lousy case and make...
Simply, you are being charged with a Class A Misdemeanor because your blood alcohol is over 0.15 (below this number, you would have been charged with a Class B misdemeanor). No need to be concerned about the obstruction of a highway charge from nine years ago--it has no impact on this DWI. Regardless, you could be looking at a maximum of a year in jail and possibly a fine of up to $4000. You need to get an attorney now to help you avoid the worst case scenario.
Crimes Involving Moral Turpitude are crimes that can make applicants inadmissible from getting a green card. A conviction for a DWI that is not considered one of these types of crimes and would still likely enable you to get a green card. However, if you have been convicted of a higher degree DWI, which could have an intent requirement, (i.e. aggravated DWIs are considered Crimes Involving Moral Turpitude) this would hurt your green card application.
It may seem like a huge invasion of your privacy--and it is--but your PO can perform a warrantless search of your home. The scope and extent can be restricted by state law, but for all intents and purposes, you will just have to suffer through it. If you meet them at the door, you don't have to invite them in for dinner, but be accommodating to make the process go as smoothly as possible.
I certainly understand your frustration and concern--you are trying to help your husband after all. Unfortunately, this is one thing you cannot do for him. It is considered practicing law without a license.
No matter how you look at it, he will do better with a federal criminal defense attorney than he would with any other option. If you are looking at for a an attorney to handle an appeal, then you have already lost, and are generally attempting to argue that some mistake of law has taken place--often a very small chance of success.
I am not attempting to wag my finger at you, but the fact that you were forthcoming only meant that you just handed yourself over to the State on a silver platter. I counsel my clients, and I will do the same for you, to never, never, never voluntarily speak to law enforcement without an attorney--certainly never without having an attorney to represent you.
Please get an attorney now, so that you can address the arrest warrant that is out on you, and can protect the remaining rights that you...