With POA, can I force my father in law to go to the hospital against his will?

The OP was asking, could s/he have forceful the elder to go to the hospital earlier, against his will. I'm suggesting that in cases in which it is clear to a caregiver, especially one who has PoA, that the elder requires medical attention but is refusing it, that calling 911 and getting EMTs to check the patient out is a good way of documenting the fact that YOU are not neglecting the elders needs.

It is hard to make the call when you are only one there when you see a problem. When needed, agreed, call 911, ask for medical and explain reason for your concern. During the evening, you can at least get them to check vitals and ER team will typically let the parent decide, if awake, cognizant, if they want him to take him to hospital to get checked out. During the day, I think the team is more experienced and they really need a 'clinical reason' to make the call to take the parent to the hospital because they do not just want to take them when they are going to just discharge the patient 4 hours later, for example. You can check for blood pressure or temperature, etc on your own, but if EKG is needed or more analysis, 911 is good place to start.

Also, it is great if you can just convince the parent you want to make sure you get checked out in case a chest xray or another lab test that urgent care or hospital can do to baseline any concerns. I think you can also call the nearby urgent care facility and ask for help and just by calling them and explaining your present concerns, urgent care nurse/rep will explain that you can explain to the parent that urgent care may be faster than hospital. Having two options/choices is better than one, but just depends on a lot of factors.

You are on the right track and the more experience you gain in having to know best option, the easier it will get to know you did the right thing. Great job engaging a second person in solving current issue.

If the EMT's come to the house they will try to talk him into going to the hospital. But, if he refuses to go they will not take him. It may be a good idea to have your dad there to help talk him into going.

I think the wise thing to do when an elder is clearly in need of medical help, but refuses, is to call 911. EMTS can evaluate and try to persuade the elder to get help. If they refuse, it's been officially documented that you sought to get them care and they refused.